So, wait, what does getting up and ornery about Shulk have to do with Tower of Smash?
I actually think Shulk's appearance bodes well for the future of Smash. It demonstrates that Sakurai isn't afraid to introduce new things and rock the boat with his roster additions. Shulk is unlike anything we've seen before, as his entire fighting style revolves around altering his stats mid-battle. We've seen transforming characters before, but those are literally becoming a new character: Shulk actually maintains the same essential moveset, but radically alters how players will fight as him. That's experimentation and it's good.
That, in turn, means I wouldn't be at all surprised if Tower of Smash is a thing. Tower of Smash, as I see it, is pretty much taking a winning formula (similar "boss gauntlets" appear in many, many other action games) and seeing how it works within Smash's distinctive playstyle. Sakurai's renowned for always pushing the envelope out and trying to improve on what's been done before. It may not always work (I did enjoy Subspace Emissary, but it does bear its notable flaws and redundancies), but at least he's trying. Taking elements from Namco's extremely successful Soul Calibur series and jiving it up with the good old fashioned Smash magic can only be a good thing.
Incidentally, people may get upset and make waves about Dark Pit being in the game, but come on, the man's literally worked himself half to death for our sake; he should be allowed some ego-pandering freebies. It's pretty much a "well done" present to himself after being nice and giving us Shulk.