Short version: 1 year deal I'd be happy with, 2 years is probably workable but still not a great idea, 3 years is silly.
Long Version:
Kovalchuk pretty much has a no trade clause whether it's in his contract or not, put yourself in the trading teams position, are you going to make a trade for him without his blessing knowing he could retire right then? Are the Rangers going to trade him if he says he is not going to report so they can carry his plus 35 cap hit without him?
The only trade would likely come if he becomes a rental and the Rangers are out of playoff position. He may be more willing to move at that point to chase a Cup or play for his next contract.
Which leads to the next question, if one thinks the Rangers are a playoff team in the last year of the Kovalchuk contract (likely 2 or 3 seasons from now) why are they trading him in his last year instead of self renting?
Is the point to getting Kovalchuk to help the team make the playoffs, even if that is by whatever he does plus helping bring over the KHLers who would be of NHL age by that point?
If that is not the point, what is it? To not make the playoffs with him so they can sell him? Is it because the KHL prospects will not come over without even though Buch, Georgiev, possibly Namestnikov are on the team? Or so they can trade Zucc, who seems to be wanting to work with Chytil, for the same return they would likely get at next years trade deadline for him anyway should they be selling?
The mentoring aspect, on the ice isn't he going to be a fixture on the PP? On one of the top lines 5on5? If so that is one less spot for the Rangers to develop someone like say Buch. If he is passed by and some other player at any point during that contract ends up getting those situations and minutes, is he going to want to stick around to play on a 3rd line with sparse 2nd unit PP time?And will the Ranger reduce his role should it be warranted knowing he is on a plus 35 contract and could just retire or become unhappy? Ask oneself the same about Zucc.
If he will not come over for a 1 year deal, which with bonus money could take him even beyond the rumored 6M, even give him a full clause... I think that is a plenty fair enough offer. If it goes as well as most are predicting he can sign another contract after that 1 year deal. If a 2nd or even a 3rd year has to be added because he wants that security, shouldn't that raise some flags that he is doubting he could secure a 2nd contract after the 1 year deal and is looking at this as a retirement contract?
I'm not doubting he could be helpful both on the ice and in transitioning the KHLers, Not doubting his character.
I am doubting he ends up being traded at all. I'm questioning what he is going to look like versus NHLers rather than the KHLers, and I'm concerned if he does not perform well he is still going to be given playing time above others only because of his veteran status, his contract, and his connections. I'm wondering why it has to be a 2 or 3 year deal versus a 1, after all, if that is all the Rangers are offering and he really wants to play for them, how is making 6M for one season something to reject given the other options are to sign a little longer somewhere else he does not prefer given if he performs well he could get another contact from the Rangers?
That is a ton of questions, mostly rhetorical, but I hope the Rangers are asking themselves the same ones.