I agree with this. I don't see much improvement with him, he's already physically/athletically overachieving and his RIQ looks to have peaked as well. He's a formidable Champion right now but I can imagine a lot of talented guys catching up to him quickly. Marquez would give him hell at 140 and 147 (still can't figure out why they've never fought), could they have been keeping Danny-boy away from the Mexican Legend?
I also don't think he'll deal well with an athlete that fights him smart. Again, Amir Khan was boxing his socks off until he got careless and set his feet too long.