Alright, so the rumored Grand Prix was a no-show... again. However, we instead got to see Star Fox content added into Starlink... again. This tells me either one of two things:
1) The rumored Grand Prix title still exists, but wasn't shown as to not steal the "Star Fox thunder" from the Starlink update. If they showed both, one would completely overshadow the other. We also have yet to see anything from Retro Studios. They're a big company, so having one team finishing Grand Prix while the other works on concepts for Metroid Prime 4 is certainly plausible.
2) The rumored Grand Prix title either existed, but was at some point scrapped, or it never existed at all. More Star Fox content being added into Starlink could be Nintendo's way of making Starlink a surrogate Star Fox title on Switch, while leaving the developmental risks to Ubisoft.
Although I'm personally feeling less confident towards Grand Prix, I'm giving the rumor until E3. If we haven't seen it by E3, then it either existed, but was scrapped, or it never existed at all. Just smoke and mirrors left by "leakers" with shaky reputations as it is. If the former, then consider all this Star Fox content in Starlink as a big Star Fox hype train leading up to Grand Prix.
And lastly, don't be concerned about Krystal not being in Starlink. It makes sense, given the setting and story already going on in Starlink. Plus, I highly doubt that Starlink will end up being considered canon. It'll likely just end up as "Star Fox chased Star Wolf out of the Lylat System", while never confirming the events in the Atlas System itself. There's still plenty of room and time for Krystal to be reintroduced in the future, especially now that Nintendo knows just how popular she is thanks to the Smash Ballot.
Don't give up yet!