I've been looking at the results of the previous primaries and caucuses for Republicans from a electoral math perspective and a few things have jumped out at me that indicate Trump will not win the nomination prior to the convention.
A few things are abundantly clear- Trump has dominated the open contest states - that is, in states where the primaries are open, or open to Republicans and Independents only. His leads in those states have been quite dramatic and tie in significantly to the increased, often record participation in the GOP primaries this cycle. His strength is coming from the Big Tent view of Republican success. Setting aside the possibility of a liberal scheme to thwart the Republican nomination process and induce an ersatz candidate to go against Hillary Clinton, that is one of the main sources of Trump's strength.
Another interesting point is that while Ted Cruz has been considered the most successful and organized caucus victor, Marco Rubio has won the one Open caucus state to date (Minnesota). That aside, Cruz has done the best so far in other caucus states. More interestingly, Cruz has a slim lead on Trump in closed primaries. Republicans it seems, prefer Cruz's brand of promised reform to Trump's.
With those factors in mind I've looked at the upcoming contests across type (caucus/primary), openness (Open/Closed/Partially Open) and delegate allocation (proportional/winner-take-all). As a caveat, I have not yet looked in detail at polling in remaining states which could change what I've seen so far.
I believe Florida could be a wild card that will change subsequent voting patterns. Another factor I have not layered in is when and if Kasich and Rubio drop out. of the race.
Aside from that. there are 1237 delegates needed to win the nomination. I cannot see a path for Trump to get above 1165 delegates prior to the convention. That's his ceiling and it's more likely he ends up in the neighborhood of 1036 delegates to Ted Cruz' 850-900 delegates. Rubio could get as high as 409 delegates but as few as he has now ~128, if he loses Florida and drops out. Kasich is a non-factor. I don't see him breaking 100 delegates and he seems to be sticking around to deliver Ohio to the eventual nominee and/or play spoiler to Donald Trump.
More to come.