No-one, of any political persuasion, should be keen to see Trump actually making it to the presidency (or even the Republican nomination). He is just bluster and bile personified, and lacks any real substance at all. Not to mention his inherent divisiveness.
Winning an early state was perhaps inevitable given his momentum, and the divided opposition he faces. Think is that he's probably already hit the threshold of support he can expect, so if he were only to face one major opponent rather than five or six then he'd stand far less of a chance of winning. Kasich, Bush, Rubio and Christie are splitting the "sensible" (relatively) vote of the Republican party. If any two or three of them drop out, then the remaining candidate will probably go on to win.
Congratulations of a sort are certainly due to Donald, though -- there hasn't been such a successful outsider campaign in a long time, if ever.