If you want an Indie character in Smash, that's great! I just would be careful with making yourself believe it's likely with Shovel Knight already getting the spotlight as an Assist Trophy. If a Smash reveal happened in an Indie Direct, it would 100% erase any interest in any of the Indie titles and direct all attention overwhelmingly to Smash, which would defeat the purpose of a Direct centered around Indie games. Indie Developers would probably not be too happy that Nintendo used a section of an Indie Direct (considering Indie titles don't get the same following as a First Party Nintendo title) not only promoting one particular Indie character/series at the expense of others, but basically not allowing them all to get some time in the public eye.
It might have just been me, but I thought the way Shovel Knight was introduced as an AT was meant to be some sort of shock. Like all the other new ones were either Nintendo or 3rd party Assist Trophies, and then Shovel Knight just shows up.
Being a "thing" longer than Shovel Knight doesn't really make you more popular or more revolutionary. As somebody who lives in Buffalo, I can make a pretty good comparison. In Buffalo, we've got a ton of different places that make some pretty bomb-ass Chicken Wings (always with bleu cheese, we never mess with that ranch ****. Get that **** outta here). Anchor Bar is the restaurant that really started the trend of the "Buffalo Wing". Duff's, however, perfected it. While the opinion on best wing in Buffalo differs depending on who you ask, Anchor Bar is considered the originator, but not the perfector.
I feel this can connect to Indies in more than one way. For example, some of the only reasons I see people say Shantae has a chance is because "History with Nintendo" and "She's been around longer than Shovel Knight".
Now, having never played the Shantae games, I'm not going to say she's not a good character. I simply don't think the argument that she's been around longer or has history with Nintendo matters all that much. I would argue it doesn't mean anything at all besides what the typical person who uses that type of argument
wants it to mean.
Shovel Knight has been on Nintendo consoles for quite some time. He has his own amiibo, with a few more on the way, and now Yacht Club games has the pleasure of owning the first Indie IP to make an appearance in Smash Bros. That's a really awesome accomplishment. That's not even meant to be at the expense of Shantae, that's just to say that that's really awesome for those folks.
Anyway, as far as the analogy being these characters to wings (mmm), basically you have a character who has been around for awhile (technically since the GBC days) and a character who has really struck that nostalgia of older side scrollers. Neither has been unsuccessful, and both would probably be really fun in Smash, but honestly I wouldn't
expect an Indie character to be playable over one that has, honestly, made more of a public splash.
I'm a big fan of Shovel Knight, but even I would be surprised to see any of those characters in a picture like this:
Bayonetta and even a character like Geno wouldn't line up there either, but I think both of those two would get in for different reasons. While I don't think Bayonetta
technically won the ballot (my guess is she was planned anyway), I think she had a lot going for her, aside from the fact that she's like an honorary Nintendo character at this point. Geno is just...Geno. He's a one off, sure, but he's been kept relevant in terms of Smash for over a decade. That's pretty awesome.