The planet Luke is found on is Rakata Prime, incidentally, the same world the Star Forge orbited in KOTOR. It even has very similar visual features. Also at least one other Old Republic reference is in new Star Wars canon. In the Star Wars Heroes app, you can unlock HK-47. Every other character in that game is from Ep I and later. Plus the fact that Swtor is still in existence bodes well. From what I have been able to figure out, the only actual canon that has been rewritten is post-Jedi (thank god the silly yuuzang vong will never exist).