It's time to settle in for another 2 months of the Republican primary, at least. Barring some miracle, this thing will not be settled until the final primaries on June 7th.
Here's how to do it. Take any delegate simulator tool - RCP has one, for instance, and set the delegates to current values. Then go throughout the rest of the primary process and allocate delegates according to each candidate's best-case-scenario. For both Trump and Cruz, probably the best case is that they win all the remaining winner-take-all states and also clear the 50% threshold in the remaining states (but barely). Absent a huge seismic shift, that's the best case result for either candidate going forward.
In this scenario, Ted Cruz comes up just short of 1,237. Depending on how you finagle the numbers, and depending on how California goes, Cruz ends up with around 1100 total delegates, under his best-plausible-case scenario. Given that he's not going to really come close to 50% in New York, the more realistic ceiling for Cruz is probably somewhere in the neighborhood of 1,000 delegates.
The scenario is somewhat better for Donald Trump, but even if he wins all the winner-take-all states, and also comes in between 50%-60% in every other contest between now and June 7th (something he has not yet accomplished even once) he comes up more than 100 delegates short of 1,237 on June 7th, where about 300 delegates will be up for grabs.
So one way or another, this thing is not going to be decided until the final day. Obviously, the not-Trump faction has as their goal keeping Trump as far away from 1,237 as possible when June 7th rolls around. Playing with the numbers, there are a lot of plausible scenarios that involve Trump needing 250 or more delegates on the final day; which he likely will not get, even if he wins California. Cruz has a plausible path to make it mathematically impossible for Trump to close it out on June 7th, no matter what, provided that Kasich exits the race relatively soon.
But for anyone in the media (or who is shilling for the Trump campaign) who wants to sell the message that this thing is over, I have bad news: the math suggests that it won't be over for more than two more months.
PS John Kasich has no path to anything, under any circumstances.