A57 isn't currently remotely aimed at a low power soc for tablet/phones, the first chip is a 25W 8 core chip aimed at their microservers, and likely the pin compatibility is also aimed mostly at microservers though it could help everywhere.
For microservers they could offer the ability to order any number of servers they want and customise how many of different types of chips they want, with HSA compatibility, they have the ability to run the same accelerated code and to target different work loads. So facebook buy 10000 servers, 2000 with chips with a huge amount of compute through a gcn gpu, and 8000 servers with arm chips to get as many relatively good performance cores into as low a power budget as possible.
No one else on the market can currently offer that, and no one, afaik has any plans to, especially any time soon.
As for low power soc's, Kabini currently is beating Intel's best atom's in both performance and idle power usage. With Beema/Mullins update they offer even better power/performance combination, improved lowest idle draw in Mullins aimed at tablets and smaller, now down to I think it was about 0.7W idle vs about half that for Arm, which is a HUGE step from where they were. Probably a bit too high for a phone just yet but Beema/Mullins are exceptionally good chips, they frankly stomp Atom in just about every single way.
Smaller process node, 22nm is a marketing name, as is 28nm. In reality ask anyone in the process node industry and they'd tell you 22nm Intel is exceptionally close to 28nm at Glofo/tsmc, 20nm from Samsung/glofo/tsmc is significantly better than Intel's 22nm. At 14/16nm(again marketing names they are still built on top of a 20nm parts) compares exceptionally favourably to Intel's 14nm.
