Launch titles won't stop existing by the holiday. If it's a big system seller it'll help sell the system both at launch and during the first holiday.
Also, whether there will be Switch 2 exclusives during the first year? Yes, yes there will be titles exclusive to a new system in the first year of that system. This isn't a pro version, this is a new system. I would assume there will be more exclusives than cross-gens.
Your plan seems like a very halfhearted attempt to actually sell this thing, throwing out a cross-release hardcore skewing game "around" launch, then waiting like half a year until the big seller which apparently also launches on the Switch. With, seemingly, the possibility of no exclusives the first year.
You realize that the Switch 2 will be their priority next year, right? Which entails trying to sell the thing, which entails exclusives, presumably a big title at launch (Metroid can't run lead, especially considering Japan), and a much less prioritized Switch lineup.