I disagree. The 13" MBA is available for $1299 and $1599 whereas the 13"MBP is available for $1199 and $1499. The tradeoff used to be performance vs portability, but the benchmarks on the new MBA look like there isn't much performance difference anymore.
I am using a 13" MBP right now, but there is no way I would buy one today. I could see the MBP line going away and the MBA line replacing it completely. Not sure if they would stick with the "Air" name though.
I could definitely see them getting rid of the 13" MBP, but it has been positioned as the model you're pushed to via anchoring, as it seems like a deal (if that makes any sense). It does seem like the MBAs are filling in this role, but I don't really see how turning every model into a variant of the MBA would match up with Apple's standard product strategy.
Agree that there likely will be some changes to the larger models along the lines you're proposing, but I think they will still be somewhat distinct from the Air.