To my knowledge Sun is now working on a new version of Disksuite. I have asked around and to my knowledge no one has any information about support or the product being dropped. It seems to have been a rumor that got started when we OEM'd Veritas. It is a better product for doing RAID configurations, etc. This product comes with all our SSA configurations under the name Enterprize Volume manager.
Simple solution is to back up to tape and re-work the disks.
There is no additional licensing costs. Solstice Disksuite, at least in the next few years, will be supported by Sun. Sun just created a new development team dedicated to the improvement of Solstice Disksuite. I would recommend going with the Volume Manager to start with. In answer to your converting question, you would have to back everything up to tape, uninstall Disksuite, install Volume Manager, set up your volumes, mount them and restore from tape.