Yeah pretty much blackdog, many mods already exist for the mod version of BM, like extended versions of "On A Rail" and bringing back other left out pieces from HL1, they have now been brought to the Steam version and can be downloaded from the workshop.
I'm quite excited to see what the community does with the content now available to them from Black Mesa, of course we will see a large wave of multiplayer maps to begin with, but given time we should see some great mods being pumped out.
Mods in mods, how I love the source engine.