I could see this being really healthy, but I get the feeling that Nintendo won't consistently patch and if they do it will be in areas that are not ideal.
The character poll, to me suggests that Nintendo is all about supporting this game for the long run. For the first time ever, Nintendo jumped onto supporting the competitive Smash scene because they finally realize just how big it is, and I think when they look at the love Melee's had, they recognize that they can make Smash 4 last effectively forever because the bottom line is we buy new Smash games for new characters.
The thing about supporting a game for the long run like this is that while it's fresh and new to the casual audience, eventually the average joe is gonna call it quits on buying character DLC. This isn't like Mario Kart 8's DLC, it's just one character - the casual consumption of Smash is probably going to end the second Splatoon comes out. However, those of us who are competitive about Smash are going to buy those characters as a necessity. For instance, if they were to add Krystal (God forbid), I wouldn't necessarily be too hyped or even want her, but how would I keep any of my friends who might like her interested in coming over to my place for friendlies? I most certainly wouldn't be able to bring my Wii U along to help a local tournament out. So, point in case, Nintendo sells me a character I would have rather never existed because I have to stay current.
This is how TCGs remain relevant and popular - ban lists, new sets, evolving metas. The difference here, that I feel puts the power in our hands, is that Nintendo will basically have to cater balance patches to our whims past a certain point, or else just drop support for the game. TCGs will always have a kid buy a booster pack and play with their friends because they watch the television show, or that obsessive collector guy will always buy a billion packs. If Nintendo screws over the people who buy DLC characters though, they'll eventually kill the market and we'll either never update our Smash 4 again, or the worst case scenario happens and everyone just goes back to Melee. Again.
I think they're on the right path right now. I don't see a future where they're going to make balance patches that aren't "ideal". Is it gonna suck when your favorite character takes a hit? Yeah. Is it bad in comparison to letting the metagame stagnate? No.