Considering they are reusing the BotW engine to make a sequel, it's not out of the question for them to do the same with Mario. Odyssey outsold BotW, after all, so there's a bigger incentive there to make a new one instead of just DLC.

Honestly, all these points come off as really disingenuous. Though, to be fair, when we talk about series like Mario, it gets a little more complicated, because people tend to categorize into lineage, genres, series, and literal sequels. For the sake of argument I'm going to try to stick to "series and sequels", though even the series part is up for debate. 

The point about titles almost works ... but it's just too devoid of substance. Super Mario World isn't a sequel to the 3 Super Mario Land games (or 2 if you don't include the 3rd one, I personally don't care) for many reasons. One of the most obvious being that it released after the first Super Mario Land game, but before the other two, so the console series and the handheld series were releasing simultaneously. Beyond that, Super Mario Land is an entire series, with three games to differentiate it, and it was marketed as such. And, at the time, Mario was mostly known for being a 2D platforming icon, so the fact that those games share very basic gameplay similarities wouldn't make Land 2 or Land 3 sequels to World. They were basically marketed as quirky handheld titles that were companions to their console counterparts. 

Super Mario 3D Land and Super Mario 3D World, on the other hand, feature much more specific similarities and gameplay aspects that aren't seen anywhere else. There are multiple series within the Mario franchise that base themselves upon 2D gameplay (Classic Mario, Mario Land, New Super Mario, etc), but there are only two games which are quite like 3D Land and 3D World. Sure, they are marketed somewhat similarly, and they share a clever naming scheme, but they have much more specific similarities - compared to Land and the Classic series, which share superficial ones. It is fair to say that 3D Land and 3D World are their own "series", with 3D World serving as the sequel to 3D Land. 

Here is a chart Nintendo themselves use for the 3D Mario games

Now to be fair, this chart is based upon the "lineage" of the 3D Mario games, which is why it shows the other 3D games as well. But, it atleast establishes an official connection. And, within that connection, 3D Land and 3D World are the only ones which play similarly. It is also worth mentioning that while Nintendo like naming home and handheld console entries differently, nobody really goes out of their way to say that the handheld and home console versions of New Super Mario Brothers are different series. Because, logically, they're all part of the same series, even if they share different naming schemes, with the handheld variants being linear in name ("New Super Mario Bros, New Super Mario Bros 2") and the home console ones taking up a console subtitle approach.  

I feel like you completely missed the point about Super Mario World 2. It doesn't matter whether or not you see it as a SMW sequel personally, or whether you see it as the beginning of the Yoshi series, or both. What matters is that Super Mario World legitimately did get an official sequel. Now, I did some of my own research into the topic and I found out that the original Japanese title of Yoshi's Island simply was "Super Mario: Yoshi's Island", whereas internationally it was made to "Super Mario World 2: Yoshi's Island". But, i'm not sure why you didn't bring up this point, as it is much more damning than simply saying they tried to cash in on the Super Mario tie-in without explaining anything in a substantive way. 

As for Super Mario 64, I'm not sure why it isn't relevant that the game was supposed to have a sequel. I mean, take a step back and look at all the games you listed, and you'll notice a problem - all of them either don't have a sequel because of a failure, or because of a logical conclusion we can draw. 

The Nintendo 64 Disk Drive completely failed and development of Super Mario 64 2 ended with it. 

The Gamecube wasn't very successful and Super Mario Sunshine was one of the worst selling mainline Mario games, so no sequel was made. 

Super Mario 3D World was a sequel, and even if you don't consider it one it was an "idea" that already had two entries, but even then it was one of the worst selling mainline Mario games. 

And finally, when left unexplained, Super Mario World not getting a sequel is a totally disingenuous point, because it doesn't take into account that "mainline" Mario games were shifting from 2D to 3D. In other words, if 3D game development never caught on, we probably would have a sequel to the effect of Super Mario World 2/Super Mario Bros. 5/whatever. It was a technological change, as well as the fact that Nintendo were busy developing a wide variety of platformers, that lead to that conclusion. Even then ... the New Super Mario Brothers series is in itself a series dedicated to continuing what the classic series offered, so it's not like Nintendo abandoned that cluster of ideas.

"Super Mario Galaxy will never get a sequel. 64 and Sunshine never did, so why would they start now?"
I should really tag this just in case there is a sequel a year or two from now, for the laughs.

Yeah, no way I'll ever respond to that.

In fact, I would love to see a sequel to Odyssey, and I really hope it will happen, it's my favourite game of all time. And since before Odyssey, my favourite game was Super Mario Galaxy 2, I can only assume Odyssey 2 would be as good or even better than the first one

So basically you're admitting that your original comment is extraordinarily superficial in how it draws parallels and conclusions, and that said conclusions and parallels don't really rule out an Odyssey 2? Nice. 

No, I don't, it makes way more sense than "SM64 was about to get a sequel, that's why Odyssey 2 makes total sense"

Right, but that wasn't the point I was making, that's just a fallacious way of simplifying it. My point wasn't just that Super Mario 64 2 was originally planned, but also that the lack of sequels to 3D Mario games have a lot to do with the success of the devices they were on (Mario 64 2 was developed for the failed disk drive expansion). Even then, I don't understand why you're making fun of that characterization, because your logic was basically to create as simplistic of a parallel as possible, which is ironically what you're making fun of. If you list 3 3D Mario games that didn't get sequels, and then someone specifies that one of them was itself a sequel to a 3D Mario game, and another one of them had a sequel planned, does that not discredit a large chunk of the simplistic parallel made? Sure, you have a pattern of Mario games not getting sequels, but without explaining that pattern it doesn't mean much. Which is the point I was making. I gave you an entire host of reasons why none of those examples are applicable - I was even fair enough to discredit my own point about Super Mario World 2 because you didn't discredit it in a substantive way. 

It doesn't take that long to read, but if you're that lazy then I suggest not making some really simplistic and poorly thought-out parallels, especially if you aren't going to justify them well. 

Odyssey's situation has a much stronger parallel to Mario Galaxy than any of those games, but to be fair I'm not saying it's  guaranteed to happen either. I'm just disappointed that I tried to be reasonable and what I get is a lazy mischaracterization as a response. 

Super Mario World already exists.

I'm not sure why people are arguing about which games are sequels or not since regardless of who is right here it has no bearing on whether or not Odyssey will get a sequel.

It's a bold claim. Super Mario Odyssey is a huge hit, critically and commercially. Do we need a direct sequel? No. Is there a good chance we'll get one? Yes.

Whatever year Breath of the Wild's sequel doesn't come out in 2020-2022 would be a great time for Super Mario Odyssey 2. I think there's plenty of ideas they could implement. Maybe they could mix power-ups with the Capture Mechanic. How about adding Luigi and finally having split-screen? Throw in Yoshi to ride as well. And don't use the tired Bowser kidnaps Peach plot. You could have different enemies. Basically, there's a lot of potential.