I have an old Binary B-500 matrix that will no longer switch sources so it needs replaced. But some of the receivers stillwork.

The question is, will the receivers be compatible with any other brands or only with the Binary matrix?

That is a big Maybe, HBBaseT has seen a number of chip and feature set changes.
In theory any should work, but reality has not shown that.
Whatever you buy, buy as a set.

Yeah, I'm thinking it won't work since the matrix I have is one that has the sending units on board, so it just has the RJ45's.

Looks like I can buy a different matrix. Get one with HDMI ports, a few short jumper cables and then get just the transmitters that match the existing receivers I already have. Bit of a kludge, but it should work and cost less.