You are forgetting one big thing here and that is platform power.
Broadwell is supposed to bring Quad Cores and basically all mobile chips into the fold of SoC designs. Haswell will only do that for the ultra mobile dual cores.
That won't make anything faster but it goes a long way in pushing total platform power as low as possible. Next to the Display that is where the biggest potential for increased battery life lies.
For high end quad core notebooks battery life should change a lot with Broadwell. It should end up almost at the same point as ulv haswells.
Quad Core Haswells get the new idle i0x state but aside from that the chipset and everything will largly be just as power hungry as with Ivy Bridge. While it may run more frequently on idle power consumption that idle power itself won't be too different. The SoC ULV are different and Broadwell will move all mobile chips to SoC.
Also die shrinks always deliver performance. What architecture changes does Haswell deliver. The CPU is the same just a bit wider same as from Sandy to Ivy. The GPU is mostly the same as in Ivy only bigger. The GPU from Sandy to Ivy is more different in architecture then now from Ivy to Haswell. The power managment and SoC for ULV is the only architectural difference. That is what Broadwell will do to only for the non ULV chips.
Core was a big difference in architecture for performance and Nehalem everything after Nehalem is iterative. Only on the GPU side one can speak of changes. Sandy to Ivy the EU efficiency of hte GPU climbed by 100%. With Haswell it is mostly more EUs and a more mature 22nm process. So the tick tock doesn't really hold true anywhere here.![]()
There is some speculation in all of this.
Broadwell is supposed to make quad-cores standard at 35W/37W, but that doesn't necessarily mean increased power. 45W chips will continue to exist, and those will still be more powerful. We don't know how much power the 35W Broadwell quad-cores will pack, but they certainly won't be ultra-fast. Performance will depend on factors such as the clock speed and cache memory, and we know nothing yet on these quad-core chips. The performance of these quad-cores may be very similar to the performance of dual-cores.
There will be changes to the performance of both CPU and GPU, and to battery life, but this is only speculation at this point. There is nothing specific on it. Haswell is not even out yet, and people don't really know the exact power of its CPU and GPU, and its battery life. Of course Broadwell will be better, but so will be Skylane and Skymount. The real question is: is Haswell good enough? Are there any specific changes that Broadwell will bring that will overcome the shortcomings of Haswell?
I don't see a reason for waiting for Broadwell right now. There will always be improvements in performance, efficiency, battery life, and so on. But is it worth waiting over a year to get the hands on these processors?