Centrists campaigned on a promise to fix the ACA. (Some) conservatives campaigned on a promise to repeal it in toto. The President, of course, aligns with the centrists.
That's reality. Also reality - Dems are united in opposition to anything coming from the GOP caucus.
So - just as was the case eight years ago when the ACA was passed, any change is going to have to be the result of a compromise that both centrists and ideologues can live with. That's why the ACA is such a mash-up. And why any fix is going to have to look the same.
What's frustrating is that the ACHA was not hastily conceived - it was intended to be an inelegant mash-up that addressed the most important concerns of both ends of the GOP coalition. For conservatives, the benefits were considerable - an end to the hated mandates, and an unprecedented use of block grants to restrain the grown of a big federal entitlement program.
The deal appears to have foundered on a late change that was a bridge too far for centrists, even as it was cynically rejected by the Freedom Caucus. Trump apparently agreed to eliminating the "essential health benefits" (EHB) language from the ACA. That's a welcome change from the perspective of permitting insurers to offer skinnier (and, of course, cheaper) plans in the marketplace. But to centrists, it was a red flag for their re-election chances. Imagine the demagoguery that Dems could unleash against the centrists in toss-up seats - in the midst of an opioid epidemic, insurers can now issue policies that don't cover substance abuse treatment!
The AHCA was always a carefully crafted, delicate compromise. Unity was precious, and the FC essentially blew that unity apart. It's hard to see how an ACA fix can be resurrected at this point. I agree with Trump that it is senseless to waste more time and resources on the effort until the GOP caucus re-dedicates itself to unity and compromise in furtherance of the greater good.