I fully expect to see a quad in a 13" Pro eventually, along with Retina. Eventually.
My current 13" Pro non-Retina is 25 W TDP for a dual core, so a 17 Watt TDP for a quad is a ginormous improvement. However, it doesn't necessarily need to go that low.
My MacBook Pro and my MacBook have similar-sized batteries, but the Pro is a 25 Watt CPU (P8400) with 58 Watt-hour battery, and the MacBook is a 35 Watt CPU (T8300) with 55 Watt-hour battery. Battery life on the Pro is good. On the MacBook it is not.
The current Retina 13" is an i5-3230M, which has a 35 W TDP, and it is paired with a 74 Watt-hour battery. That gives us a lot of room to maneouvre IMO, esp. since Haswell is supposed to give us significant idle power advantages.
P.S. I'd be perfectly happy with Intel HD 4000 qraphics in a 13" Pro Retina, as long as general dual-monitor OS usage was smooth.