The "old" OBS will be replaced by OBS-MP in the future. You will still be able to use it of course, but updates will completely stop at some point. (I think currently the guys work on win10 support for both OBS and OBS-MP)
If OBS-MP has all the features you need, I would probably recommend to already switch to it. But you will have no problems if you keep using OBS for the time being.