Whether Republican moderates always cave has been the issue du jour of late even before the news that Senator Heller will not support the bill "in this form". Some have argued the Senator's statement means he will not vote for the bill because pressure from the most conservative Senators will prevent the bill from moving further left as he would require to support it.
But for moderates to vote for the bill, only the optics of moving to the left matter. That means throwing a few billion their way, but that is only a token which can be easily undone in future legislation. Likewise for extending the Medicaid cutoff date. Medicare is being reshaped with this law from a benefit promise to a contribution promise, which is more easily controlled or eliminated. The radical reshaping of Medicare matters, not the exact date it happens.
This is not a prediction site, but I can not imagine the Republican bill will be stopped by Republicans. The safest bet is that the Senate bill will be changed slightly before passage and will then be passed by the House as is before the July 4th holiday recess.
Part of the Republican calculus will include allowing two so-called moderate Republican Senators to vote against the bill so that their seats can remain safe. Heller may be vying for one of those two safe spots. Susan Collins may snag the second spot, but let's see which Republicans yell the loudest about the bill over the next few days.