if they really wanted to hype up a Smash game, they certainly wouldn't use Krystal. She pretty irrelevant atm when you compare her to the rest of the current newcomers. She hasn't been in a game in over 8 years (thats almost a decade). As a side character in Star Fox... she would at least need to make another notable appearance for her to be considered somewhat likely.
I mean... the only newcomer i could compare her to is Palutena who is a side character of Kid Icarus. Only difference is that Palutena has made a recent appearance, has some fan demand (i know ppl who weren't surprised that she was in), and was in a game Sakurai worked on himself.... So she had alot helping her chances... with Krystal, there is not much going for her other than a small fan following on a couple forums.
Theres nothing about her that makes her "high profile" gaming character that must be included in Smash. Shes not a retro character with an iconic legacy (Pacman, Little Mac, Megaman) nor does she have the flavor of month thing going for her (Greninja, Rosalina). Shes just not that important to nintendo. It'd be easy to see why she'd be excluded from the roster.
Here's the problem: We can't say
anything about relevance when it comes to Star Fox (well we could, but it wouldn't get us far). Command is technically the last
new addition to the franchise. She was in it. Yes, we could debate the fact that Command came out 8 years ago.
However, I think many people don't understand the thought processes that have transpired during the development of nearly every Star Fox game. The franchise is unique
not in the sense that it is just a major Nintendo franchise, but in the sense that it has become a franchise that will clearly (after Command, given Miyamoto's recent interviews) attempt to
innovate before its release. This is why Miyamoto stated that he has been working on the conceptual phase of the new Star Fox game for
over 6 years. For better or for worse, this is the truth.
This is not the first time Star Fox was used to innovate (even so, we don't know too many details on what they're planning to do for the Wii U Star Fox game). Check out
the history of Star Fox, as it might surprise you. Pay
close attention to certain details for Star Fox on the SNES and on the 64; focus on the details pertaining to their respective innovation. You'll see what I mean.
This franchise is near and dear to Nintendo's heart. Whether or not it's popular (which it arguably is, having a combined franchise sales of roughly 11 Million, even with just 7-8 games, as well as having a considerably passionate following) among the fans hasn't detracted from Star Fox's Smash representation.
In the end, it's up to Sakurai and his team to decide who will make it and who won't. All we can do is support the characters we'd like to see in Smash, and the rest becomes history.