It's not a belated push.....
The ARM ecosystem 5 years ago was not what it is today. HD Graphics, HD cameras, interent connectivity 5 years ago all were the goal, the dream. What ARM was back then was cheap, and used very little power. Today ARM is still cheap, uses quite a bit more power the penalty for a much higher performance envelope.
Lets switch to x86 from both Intel and AMD. 5 years ago x86 was power hungry and high performing. Low power was the goal, the dream and it took 5 years for x86 to evolve itself downwards to the point where is just now competitive with ARM who has evoved itself upwards.
ARM has always faced this performance ceiling and the consequences of it, when does x86 become a better solution than ARM? With all power consumption and performance curves being equal I would prefer a smart phone or tablet or notebook that runs compatible software. Notice that I said software not apps. An app is something that you eat before your main meal (for us colonials). You limeys call them starters.
So Intel and AMD have not entered the phone and tablet space belatedly, it has been a steady evolution downwards.
Intel has been so busy competing with AMD on the bleeding edge that it took a sea change in corporate design philosophy to entertain the concept of low perfomance being "good enough". That is what AMD has been saying for years. So we now have a knew race downwards. You can't have low power and bleeding edge performance, at least not with today's understanding of physics. Yes there are fabrication techniques which help such as FinFET, but power equals performance.