a few things wrong
traditional sports have changes to them over time, although yes very slowly
league also changes and will keep changing over time -- new champions, and patch changes
Eventually there will be too many champions, since league has been cranking them out so hard in such a small amount of years
the changing thing isn't a huge deal, as long as the new game isn't too different, and that it's overall better (like how Melee was more of the same of 64 but improved on it and had a larger cast and better graphics and thus had a visual advantage both for players and spectators)
with a game like sc1 bw, it was able to grow huge over a decade, but look at league and how fast it grew in a few years? Thankfully the changing aspect isn't a huge huge thing. I'm sure we'd all be happy enough if a smash game was able to reach anywhere close to starcraft (at least several teams that can support 5-10 players each)
The biggest thing in the video is the accessibility. This is slightly hurt by how there are different smash games. But the biggest thing is that as a console game, it lacks so many features that help esports become esports. You can't log onto smash online and immediately enter a social area. You just play. League is huge because it's a social game and there's tons of rewards (skins, etc. that you can show off to others). Unless Smash can support this kind of thing, it will be heavily disadvantaged. Not everyone plays a game to be a competitive player. You need a huge casual base too, that's where the support and viewers come from. And that's a huge reason why people become good at a game too, so they can show off to their friends. League and to a lesser extent Starcraft have a huge social aspect compared to smash. Thankfully since smash IS a fun party game, it's not completely lacking in that aspect, and this is why I love smash and support it as THE fighting game. Just that having to play in person is still not as good as playing online behind your computer. (Unless you play online and use skype or something in smash... still not the same and takes more effort)
Also competitive smash (unless 2v2) is a solo player thing, which has proven to be largely disadvantaged compared to team games (starcraft vs dota and lol). To be accessible it has to be social, and it has to also make it comfortable playing for the lowest common denominator (meaning people who need to blame others and can't handle the stress of playing a competitive game and losing solo)