Both Solaris and AIX crawl on, particularly in the banking sector where there are decades old applications that still need a platform to run on. A bank I worked for 7-8 years ago had a project running to refresh the hardware platform for both for the next 10-15 years.

IBM of course has the resources to prop up AIX as long as it has customers that depend on it, whereas Solaris is now pretty much dependent on the community. At least it is based off of SVR4 and not SVR3 (like AIX), has source code available, and runs on x86. Not sure that will be enough for it to survive into the future though.