After checking notebookcheck.com, the 460 pro with 4GB is on the "high-end" scale but at around rank 75. It's not exactly a gaming GPU, but more focused as a "pro" card for video professionals. It probably can play a decent amount of games from the last few years on medium settings with a decent fps but not to many newer ones (assuming your running Windows). However, the biggest problem with gaming on laptops is heat. With the MBP size, quick heat exchange may be an issue when gaming. Yes I know they claim to have a "revolutionary" heat system packed into it, but heat kills laptops. That's why most gaming laptops are very large, to allow larger cooling systems. Most gaming laptops are not aiming towards a super light-weight portable machine but rather a game-power station with efficient airflow. size doesnt matter. The new Nvidia GTX 1000 series GPUs are very power and heat efficient chips to the point where laptops can be made quite a bit thinner without performance hits on new gaming laptops (last gen the GTX 900 series mobile chips have about 25% performance loss over their desktop counterparts but that's another story). So yes, for the price of the new MBP, you can get a gaming laptop that will run circles around it. But you have to remember, the MBP is not a gaming machine, but more focused on a portable work station for photography and video edits.
BTW, I have a gaming laptop (ASUS G751JY) it can play all games at great fps counts with it's GTX980M. However with my job, I do not have internet almost all of the time and just about all games today, even through steam, required internet connection to verify that the game is real. It's called DRM or something (Digital rights management.) I didn't know this when I bought it and I cant play any games when I have no internet connection. Big bummer. I assumed that you bought the game and that was it. So I will be getting the new MBP and shift gaming to my PS4.
In addition, SSD's don't make gaming performance any better, they will load the game faster yes, but will not give you a jump in fps.