There's this impression that O-Line Reproductions is a "new company," but there's no evidence of that. By all indications, Heartland Hobby Wholesale, a distributor, bought the remaining RMT stock that RMT probably could not afford to take in entirety. The RMT "STO (ship to order)" policy seems to point in that direction of thinking.
"OLR" is just a name that Heartland Hobby Wholesale put on the box, probably to avoid any warranty, liability and clarity issues. There's no indication either on the HHW website that they are continuing the production. There's not even any mention of OLR under their product lines. Then again, several on their staff are TCA members, so maybe there is or was a thought on this. But seeing how well the O-Line Reproduction stuff sells before making any decision.
The other consideration is that the tooling and dies are still owned by Kader as much I have heard. And being that they dropped some 60 other train makers several years ago... train makers who were well established... why would Kader want to deal with a wholesale distributor directly in this manner?
But then again, it's funny how old tooling and dies keep coming back into production. Anything is possible, but there needs to be a market for it too.
Most of the track sections and pieces you have listed were not even made by RMT, or available under the OLR banner. They were made originally by K-Line and just how available they all still are... well, you'll probably have to do some hunting on the internet.