First off, Milwaukee's a team that it seems like you can easily pick on when it comes to trades/free agent signings (that Mo Williams trade was terrible, and Charlie Bell and Mo Williams were nearly signed away from them by Miami prior to that). So I guess you can make a case that getting Sessions isn't out of the realm of possibility--Scott Skiles misused Sessions earlier in the season because for some reason due to his desire of Luke Ridnour's game, so apparently they don't appreciate his game as much as other teams do.
But at the same time, let's be rational here--it's virtually impossible to get a young player on the rise who's already so productive in the assists category. Sessions clearly has pure playmaker passing ability, and I tend to believe those are now more desirable because many of the defacto PGs nowadays are gunner combos. Another thing about him--he can really get to the free throw line, and that in combination with his passing ability makes him quite unique. The Bucks would absolutely horrendous to blow this one--Sessions is really good and really young, and although $$$ could impede them, they really should look to move Jefferson, Ridnour or even Redd to create the capspace to retain him. Again, there could be a Gilbert Arenas situation where he leaves to follow the $$$, but Arenas was a scorer first, passer second; this guy is a passer first, scorer second (and he's still a very good scorer, considering). I tend to like the latter better, but I just don't think it's plausible for us to get him.
Even if we get to phase II where he spurns the Bucks (highly unlikely), we'll probably have to start a bidding war with several bottom teams because after all, he is a hot commodity. We can offer him the starting PG job, but I don't know if that will put us over the top with him. But again, I doubt we would even get past phase I, if the Bucks have a brain.