I agree with you 100%. It will not hurt boxing since those crossover matches have been around for a while ( I am pretty sure even Mohammed Ali had one, and just got leg kicked.)
But it will give MMA more exposure and will be a great payday for everyone being involved.

I also dont see McGregor taking this onebut I sure hope, he will put up a good fight, as he will play a lot of touch butt in the park as Nate Diaz would say.