The short and simple answer is there are none, there's no magical unlocks at the 'end of the rainbow.' Over this past 2XP weekend I finally, after days upon days of playing, reached 'Master Prestige.' So my assumption 'was' that there would be some obvious benefits like in past CoD's; e.g. all guns unlocked, killstreaks unlocked, perks (are), etc. But Noooooooo!
Instead all you get is an icon and a background - period! BTW...I still prefer my BO2 Master Prestige background.
Worst when anyone sees a Prestige Master ... many leave the lobby. Also what's with the  in-front of the icon?? Shouldn't it just simply be the icon by itself? Frankly the whole 'Prestige' process is boring and uninteresting and sadly without any real purpose. Once you have enough Tokens, buy anything you want with no waiting. As a balancing I much preferred the Level X = Guns 'C & D' and Perks 'E & F' approach and the Prestige 'permanent unlock' benefit.
Further, even the process of unlocking appearance and patches is convoluted and uninteresting.
So now I'm a Prestige Master ... whoopee doodle!
I agree with you. Also got my last prestige. But now what to do? Having more then 600 squadpoints, I'm going buy weapons and with the future ones unlocking everything for each soldier.... but after that......??????
Perhaps they will implement an option to buy camo's with squadpoints. For at least 2000 squadpoints (and going up). Now you can only unlock some special camo's/uniforms for playing clan wars. Guess what... Not everyone is in a clan, nor want to be or aren't good enough to get into a clan. Letting them buy uniforms/camo's is more challenging in my opinion and that way fair for people who don't play in clans.