There are three lounges that are officially exclude in Honors T&Cs and will become accessible to Diamond Reserve members. No downside there. But there are few hotels that do this outside of program's T&Cs, I recall there's some Conrad in UAE (Abu Dhabi I think?) that has a proper lounge only for guests at its equivalent of executive floors, and has some pro-forma inferior lounge for Diamonds. I'm worried this will become more common, now that Hilton plans to introduce more "premium clubs". I'm inclined to believe that these premium clubs will be closer to the current offerings and the "regular" lounges will have worse offer.