I don't see a problem with converting it to Black Mesa.
The problem is, it probably won't come out for at least another year. I have recieved NO updates on their progress for a while so I doubt they're close to done if not haven't given up. From the trailer it looks like Black Mesa graphics will be significantly better than HLS, so I think it'd be kinda cool to see how it looks on Freeman's Mind. I know alot of people are concerned about the game looking classic but since Ross Scott is using cheats and not playing the traditional way, (skipping obstalcles and climbing things that you can't normally climb, because that's what a real person in such a situation), he may as well upgrade to Black Mesa. But like I said, now that The Tunnel is finished, FM epiosdes will be coming out alot faster now so unless Ross starts another big CP project again he'll probably be done by the time Black Mesa even comes out.