On the next MBP you could expect an expensive SSD BTO option (low capacity and slow compared to any decent and much less expensive high-capacity 5400 or 7200 rpm drive). So far every affordable SSD has underdelivered. The few notebook SSDs that really shine are far too expensive and yet they still offer minimal capacity. They're simply not there yet. Once they're twice as fast and only twice as expensive as 2.5" HDDs, they'll start to take over on the mainstream market. Specifically in Apple world, among MBP customers there are far too may people who require decent capacity and/or high performance. Apple knows that and they will not piss those people off just so they force a new technology (that BTW also costs Apple more to use) onto them.
I'd expect to see Apple keep the Combo on the low-end MB.