What if hes already agreed to join us and the negotiations are simply between the clubs. Man City, Chelsea, Liverpool, Arsenal may be interested but what is that worth when they say "Well pay Bayern 35m" they accept and then Kroos says "Erm actually ive agreed a deal with United" then its up to the club to keep him or negotiate a better price for him with United at which point there is no reason for another club to even bid.
The market price of a top player in the last year of his contract seems to be in the region of 20-25m as seen with RVP who was MUCH MUCH more important to Arsenal than Kroos is to Bayern, who is essentially a stand in for Thiago. The only rival I could see going in for him would be Chelsea, but I dont think hes really the type of player Jose needs in his current team.
Also we cant under-estimate how much of a pull LVG is for German/Dutch/Spanish players, hes essentially their version of Fergie (Less accomplished ofcourse).