Can't know for sure but I think that he would have still wanted to go regardless but perhaps wouldn't have been allowed to again. Had Spurs made C.L, Harry may have stayed and Levy would have been able to force Modric to stay again. With AVB going there I think they have sold Modric to give AVB some cash to work with as much as anything and it was harder to keep Modric with no C.L football + Madrid banging on the door. I think Modric also put himself in the window with good performances in the Euros.
I think he was going regardless. I reckon they did a Ronaldo and just said he could leave in 12 months. Why else would he have played out of his skin? He could have gone on strike as he eventually did anyway