I don't see this as a reboot or some sort of alternate reality. The Legends banner is simply a tag to place on all the old novels so they aren't confused with the new ones. So someone won't go into a bookstore looking for Heir to the Jedi and accidentally buy Heir to the Empire, thinking it was a sequel.
This is why I don't think it will affect the RPG at all. (or video games for that matter).
It's not a reboot of the timeline in the sense that the new Trek movies are. It is a reboot of fan expectations. Let's be honest many of us fans had given up on post RotJ movies especially after what Lucas did to the Prequels. So for better or for worse we had to look at the EU as canon of what happened after the defeat of the Emperor. If they plan to make new movies they had to reboot those expectations. If they ever plan to make movies in the Old Republic era, I'll bet we see a reboot of the Eu there too. It just make sense to untie their hands.