They'll keep all three and run them on POWER.
The SPARC architecture is what is most likely to see an immediate fall of in investment.
IBM doesn't really care what OS you run as long as it is seeing a slice of the pie.
For instance "IBM" (read IBM Software Group) will happily recommend Windows on a cluster of x86 servers if you are considering WebSphere, they don't even care if it's IBM hardware (the margins are poor anyway) .. all the more cores that you need to be licensed for.
"IBM" (read IBM Hardware) will happily recommend AIX, OpenSolaris or Linux running on POWER for the same solution .. they don't (really) care if you use AIX, they may mutter something about it being superior but at the end of the day their commission is based on the tin.
IBM is not one company. Not even the hardware division is one company, try asking your rep whether a System P solution or a System X x3950 x86 Nehalem solution is better for a DWH and watch them go apoplectic. They are getting better at showing a unified front but its still like dealing with 6 companies.
My prediction:
1. POWER7 (2009?) will support Solaris
2. There will be no more development of SPARC based systems, the tech will be immediately raided for goodies for POWER/Cell.
3. Solaris on System X will be a supported config
4. By POWER8 (2010-11?) all of the Solaris goodies will be ported to AIX (Containers .. WPARs were half baked anyway, ZFS) and new customers wont choose Solaris unless they are ideologically bound. This will lead to eventual natural demise of Solaris by 2013-14.
5. Glassfish will either be gutted or rolled in to WebSphere CE. More likely to be gutted, IBM needs a better product to compete with JBoss at the low end of the market.
6. StorageTek will be immediately rolled into System Storage.
7. Netbeans will be rolled into Eclipse.