Yeah I'm on the new game train, though like Splatoon 2 it'll be using it's predecessor as a base. Cannot wait to see gameplay!

All of this "new information soon to come" and mystery behind the trailer would not be used for a simple port. Also everything else the others are saying a damn good evidence it's new. Or they pulling a Capcom and it's "Super Smash Bros Ultra!"

I'm on the side of it being a new game.

-I don't think Nintendo would be this ambiguous about a port/enhanced port

-Unlike MK8, I think Smash 4 got enough sales to justify moving forward to a new series entry

-I don't think Nintendo would spend the money to make a CG trailer announcement for a port of Smash 4.  Look at MK8:D, Nintendo didn't even announce it on their Switch presentation; instead, they just threw a video on their youtube channel.  If this Smash was a port, it wouldn't have this much fanfare.

-Based on the reveal, it looks like Nintendo is looking for Smash to play a big role in carrying the Switch and its online service this holiday and I don't think a port can do that.

-If Pokemon can't make 2018, Nintendo is going to need a big title to carry the 2018 holiday season and the only plausible game right now that can do that is a new Smash.

-A new game means a new DLC/amiibo cycle which equals more money for Nintendo.

-Smash 4 started development in March of 2012 and was released on Oct/Nov 2014 with Sakurai doing two versions.  Smash 4 development ended at the beginning of 2016 and if Smash 5 development started immediately after that and is released at the same time as Nintendo's paid online in September, it would give Sakurai about the same amount of dev time as Smash 4 with him only having to focus on one platform.

Imo, it's a new game built from the foundation of the Wii U game. Much like Majora's Mask from Ocarina of Time or Galaxy 2 from Galaxy 1. I think this is how they're able to make it significantly faster than other Smash dev times. If it was just a deluxe port I don't know why Nintendo wouldn't have been upfront about it and also shown us proper gameplay footage. The different developers seem like a big reason against it being juts a port as well. Also, the logo looks different from the Wii U one, and why does the title say pending? If it was just a port of the Wii U game, why not call it Super Smash Bros for Switch? Makes me think it will have a title like Melee or Brawl. I was predicting the Wii U one to be called Rumble, but maybe they will finally use that here. 

I believe and hope it's a new one.

I feel like this is somewhere between a new game and a port. A brand-new smash seems unlikely given all the stuff Sakurai said before (especially in just 4 years). However, the way nintendo revealed it, it will not be just an enhanced port either.

So basically smash 4.5. Using the Wii U smash engine at its core, but making heavy changes all around it (e.g. a full fledged story mode).

Besides it being only 4 years apart from the previous game, What other evdience that people think this is a port?

It's almost certainly a new game. The copyright is for 2018, and they list the original developers of the IP as Nintendo and HAL Laboratory. This is something they did during the reveals of both Brawl and Smash 4, even though Brawl was partially developed by Sora Ltd. and HAL had no involvement in Smash 4 at all. Other evidence includes Link using his Breath of the Wild appearance and the Smash Bros. logo being completely different from Smash 4's.

Certainly It's not simple port in any case, in worst case its hole Smash Bros 4 content for Wii U and 3DS combined, with addition with new stages, fighters and mods. So Nintendo could easily call that game like Smash Bros 5.

So I am not still sure is that a case or it's totally new game, but that's not really matter, game will be very popular and it will have huge sales in any case.

I hope port version.

Because the new game gonna be more exciting.