The price tag will probably prevent that. It would be speedier but nobody would be able to afford it.
You can contact Microsoft Customer Service and ask them if it is even in the works. I doubt it though.
The i5, no matter what model version, should be a quite capable enough processor. My personal scratch built desktop flies like a rocket and it is the 4200U. The i3 would also have been a good choice as well.
You have to remember that these are tablets. A XENON version would probably be out of the question and the battery would last about 15 seconds. BUT, it would be a glorious 15 seconds!
I knew about 2 months before the 4300U availability and have been waiting before getting my Pro 2. I will be ordering it next week.
I had been watching this thread for a while and was wondering why everybody was going after tidbit speed increase when the i7 was really what they are after.
A $2,500 or $3,000 tablet would probably not be worth it though.