Most of theses trades heavily benefit the Rangers. Rick Nash, even with salary retained, isn't worth a first round pick anymore. Marc Staal and a 2nd for a 4th would never slide; it would have to be closer to the Dave Bolland trade. Like Staal and a good prospect like Chityl for a 3rd and 5th.

Vegas already has a surplus of bottom pair defenceman, they wouldn't give up one of their best forwards for another.

while you're right, involving Chytil here is a criminal offence

I don't think you've got anything right here;
-Grigorenko signed in Russia
-Andersson will get the max contract
-Jagr will never get a 3 year contract and for good reason
-no one wants Staal (someone should put up a disclaimer for Armchair GMs), just buy him out
-Marchessault isn't available and I doubt anyone is high on either Gropp or Holden
-Ehlers is a future top line player, so they won't trade him for 2 middle 6 pieces
-that offersheet is not going to happen nor is it a good idea

Jagr wouldn't get a 3 year deal, that's a 1 year deal
Saying sign Grigorenko before going home
How is the offer sheet a bad idea? He's a top line C with another 12 years of productivity? He hasn't even reached his prime and still got 70+ points this year

misread the Jagr thing.
Grigoremko is a goner. his KHL contract is signed.
few players are worth 10 million; Draisaitl had one good year alongside McDavid. you can't possibly say whether he'S worth it at this point so it would be a huge gamble even eithout sacrificing 4 1strounders. his edmonton contract should be around 7,5M.

as it is, in the next year you have 12,5 in capspace to sign:
-Miller (expect a 2M raise, ~4,5M)
-Vesey (expect bridge deal around 2,5Mx2)
-Ehlers (big contract >5M)
-Skjei (either bridge deal, preferred big contractg ~5Mx5)
then you need another 2 forwards (Chytil on an entry level deal, another ELC/minimum player)
then you need a backup goalie and you need to resign Graves (should be a cheap bridge deal)

the next year gets even worse with Buchnevich, De Angelo, McDonagh and Bereglazov being due for new deals.
essentially you have to shed 8-10M in salary every year to make this work. management probably sees Zibanejad-Andersson-Chytil as longterm future on C, so even if your plan works out, the team will be screwed in the next few years.