Up to now IBM has still had the ability to be its own and possibly some others' foundry. In that sense, it provided a key service, enabling some projects at other companies, who potentially were trying to close with a commercial product. With the sale, I imagine it could be more limited in the foundry choice. A fabless firm is generally successful by managing all the foundries.
Ya - this is the important part. IBM still retains its high end server business, and Fishkill supplies all of the processors for those boxes, built using a very custom process that you can't buy at a "regular" foundry. I doubt that it will be easy to sell Microelectronics Division while maintaining the supply of high end server chips - because it's a money losing proposition for a foundry to build that chip.
Power PC reminds me of old pal of IBM - Apple and Motorola. Apple may find something lucrative in this deal and they need partner complement their capability. Also main asset may be IBM people. Apple will love to have them in their team.