You do bring up some good points. I should be fair, and acknowledge that not all crews dislike the Ren equipment, but I know that many do (this is based on communication with crews on recent trips on the Ocean, and from other's reports of those in the Corridor). Now to be fair, there is nothing statistically reliable about anecdotes like that, but there are certainly enough crew members (and passengers) who have their issues with the cars. Personally, I find the sleepers to be quite nice (although the corridors are so small it's silly), but I don't care for the coaches at all. The single seating option is nice, but otherwise I find them to be a real nuisance to sit in for more than an hour or so (although I've still made plenty of 15+ hour trips in them). Still, they're a decent enough way to travel, and I'd still pick them any day over a car, bus, or plane.
Yes, in terms of the rough ride the track is more the culprit. For that, the HEP-2 and LRC cars fair somewhat better due to their weight, but can still be very rough on sections. We can hope that current track work will help some of that, but...
In terms of plans to remove Ren cars from service, this is what I have heard from reliable sources about what VIA is in fact planning (although this could change with time). The primary reason for that is the cost of operating them vs. the revenue they generate...yes, in order to increase capacity they will need to keep many in service, but if that doesn't happen (if we see cutbacks, for instance), the Ren cars will be the first to be sidelined, simply as a cost saving measure more than anything. Yet as you mention, their are hopes to increase service, so the Ren cars would need to be a part of it. Looking at the new federal government, and the promises of "belt-tightening" (as you mention), I fear for what VIA will have to deal with in the future. But we'll try to keep this away from politics
As for the LRC rebuild program, I expect that will speed up in the near future. Remember when 6400 was the first of the F40's to be rebuilt? It was in the shop for quite some time, and then it was also quite some time before 6402 came along. But that was with the necessity for testing the prototype. Now they're popping rebuilds out pretty well every month. So expect the pace of the LRC rebuilds to pick up once the prototype is through some more testing.