If it's the new "unrepairable" form factor, then a 13" Retina Macbook could be nice IF the price is not excessive like for the 15".
But if it's not thinner and lighter, or if it still doesn't have real GPU, then there is absolutely no point in a 13" Macbook Pro when you can have the Macbook Air that does the same thing but thinner and lighter.
By the numbers, killing the 17" probably makes sense, but in term of long term strategy and product line strategy this is pretty stupid because some people actually need the 17" sized screen, when in contrast the 13" MBP could've been killed because it really is useless (and I had both a 13" Pro and Air).