Why would you want to go back to the bad old days when you had to own 3 different GPU mantle Is only for AMD anyway NVidia have won the gpu wars with G-sync I have see it and trust me it a huge game changer than mantle something which get eliminates screen tearing, VSync input lag, and stutter is a much bigger thing than mantle will ever be
Bf4 one of the biggest games of the year it will be judged from where I'm sitting. Not a lot of care for any of the mensioned games that mantle supports after that. Outside of star citizen which is not released till 2015.
I'm not planning on replacing my three Dell U2313HMs or HD7970 any time soon, so something like Mantle that, hopefully, will help bring more consistency to frame rate output will be welcome. I don't use V-Sync because mouse movements feel really sluggish in comparison to without it.
Mantle should increase min/ max FPS in titles that support it correctly. Bf4 should show us on a high end title what we can expect. Even if its just some min gains that's still useful as in some cases it's the difference between playable and not. G sync like mantle has huge potential. Personally think both succeeding would be good for us users as long as they are cross compatible.