If you seriously think at 34 and fighting again to be Polands number one he is going to hang around because he is paid well then go back to Legia your mistaken.
This is the guy who turned down a contract extension with Viola and held out for an EPL club to get him he was that desperate to play in the EPL. Was a gamble as his stock was low at that point and he could have gone unpaid a lot longer than two plus months he did.
Is Forster the better keeper, well time will tell but if Boruc goes in wake of Forster being bought its still back to square one on keeper front
Forster is also less injury prone. Boruc only played 20 games in his 1st season and 29 last year in fact 4 of the last 5 seasons have seen him play less than 30 league games. Fraser Forster has played 33 league games or more in every one of the last 5 seasons. Forster is 8 years younger and improving. Boruc won't at his age.
