I wrote a piece about the dynamics a while back. I think the big unknown right now is whether Trump's unprecedented popularity in the polls and on the campaign trail are going to translate into actual votes. I think a lot of people, for whatever reason, just aren't believers yet and it will take Trump showing well in Iowa when actual votes are cast. I do believe this is going to happen and when it does, some campaigns will have to face the music. There will have to be a "come to Jesus moment" for the Establishment GOP if they expect to make any sort of viable run for the nomination. The big money donors cannot split their resources between several candidates and have any chance of success.
After Iowa and NH, expect to see several Establishment candidates pack it in and call it a day. The EGOP will coalesce behind the strongest showing candidate and hope they can catch Trump. Several already have some problems. Rubio, for example, has very little organization on the ground outside of Iowa and NH. Christie is doing well in the Northeast but that's about it. Bush has deep pockets but no support. Kasich is putting all his eggs in the NH basket and praying for a miracle at this point. The rest are on life support.
By Super Tuesday, I think it's going to be a 4 man race.