It's funny though, so many people think they won't patch if they need to.  

And they will need to.

Short Answer: No

Long Answer: Noooooooooooooooooooooooooo

Longer Answer: No; large characters almost never end up top tier in any fighting game ever. The tournament isn't high level play for one, people are unfamiliar with the tweaks made to the cast and don't know the ins and outs of this particular version of Smash yet for two, and the game itself isn't released yet in the first place, meaning that there could very well be plenty of buffs and nerfs to come. It's also worth noting that Bowser is still very, very slow; he's faster than Brawl, but his moves still look horribly unsafe. Players will figure out how to punish unsafe moves.

I think a more apt comparison to a character from past games is Ike. Bowser may very well be the Ike of Smash 4: Everyone thinks he's broken during the first month or so of playing the game, then you figure out how to get around his moves and punish his attempts to get in, and he drops to low tier pretty quickly.

Ike is Mid Tier.

Bowser can be high tier if he can hit hard enough.  Snake is one of the tallest and heaviest but still one of the best characters in Brawl for his range, surprising speed in his jab and tilts, and his projectile(s).  

Ike is 23rd out of 38, so low-ish tier.

Theoretically, yes, Bowser could be top tier if he could hit hard enough. Then again, you could make any character top tier by letting them hit hard enough.

Snake is certainly high tier (although he's fallen a bit since Brawl's release), but, again, as you mentioned, that's due to his range, speed, and effectiveness in projectiles. Bowser has meh range, still subpar speed if this video is anything to by, and his only projectile (if it can really be called that) is his neutral special, which has awful range as far as projectiles go and isn't exactly an effective zoning tool like Snake's.

True, but it would be a waste to completly disregard a major feature of the game.

That's why no character will ever be as broken as that damn MK! Seriously, I don't know what was Sakurai thinking with MK!

Well yeah.  But a character like Wario has terrible range but hits like a truck, lives forever and has good speed in his aerials and air speed; he's one of the best in the game.  Bowser could be the same way. Maybe he has superarmor on some moves and/or good grabs?  Don't know but it's entirely possible for him to be high without being small and fast - look at PM.

Pro players have been doing it with items for years.

You have no idea how ecstatic I was when MK was deservingly nerfed in Project M.

Yeah! Project M pretty much fixes most if not all the things which were iffy about Brawl's gameplay and balance!

i played Smash 3DS at an expo last week. played Bowser and he was very buffed, i think he is an actually viable character now.