Although i think Thunderbolt is a great interface, I don't see many reasons to have your decisions depend on it.
Would be different if we were talking about buying a portable (and even then).
The new Intel generation is mainly more power efficient, and doesn't bring real additional computing power.
To my opinion - if it's not for slave purposes - 16Gb is the baseline for a music PC, and the extensibility to 64Gb is definitely wellcome, certainly if you are using a lot of sample based instruments.
VIPro now allows you to use less memory by optimizing loading from SSD's, so that reduces the need for "real big memory space" to some extent. So yes, 32Gb will do the job, if you have a decent SSD.
If you're using may different instruments at the same time - it's better to split libraries over multiple discs, but of course that comes at a cost.
Really depends on how much "instruments in parallel" (with different samples) you need, and how often you need it ...
(if it's just now and then, you can always bounce some tracks)
In short :
- don't spend money on the new Intel chips, unless you find one with a better performance / price ratio (if you have enough $/€, don't forget to look at the Xeon based systems)
- start immediately with 8 Gb memory cards (at least 2), so you have room for expansion
- SSD system disc is nice, but not mandatory
- really fast SSD(s) for the samples
- seperate project/audio disk : type /(no) RAID depends on your specific needs
Good luck !