I doubt this will affect his stock at all. Teams know of gay players in their organization for years. If they can play, they'll pay them and play them. Lombardi and his team knew of a gay player and Lombardi told his assistant coaches that if he ever catches them questioning his manhood or making gay slurs, he would fire them on the spot.
Sure, there are a lot of people that are not the same way...but this was in the 60's and the point is that it's an example of a team knowing full well of a gay player and handling it just fine. If they have the skills, they'll play them and pay them. If they don't, they won't.
I'm a bit conflicted because I'm not sure what Sam is doing is more admirable than the gay players that kept it quiet out of fear of public backlash. And I'm not really sure why they should have felt obligated to come out since...it is technically nobody's business. OTOH, it may help those who are ashamed of their sexuality.
YR