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This question has been asked before, several times.
Anyway - the next major releases of XOOPS are 2.3, and later 2.4.
At present, it is not possible to update from 2.2 -> 2.3, due to changes of the code. However it will be possible to update from 2.2 -> 2.4.
So the upgrade route is:
2.0 -> 2.3 -> 2.4
or:
2.2 -> -> -> 2.4
It is possible to "downgrade" from 2.2.x to 2.0.13.2, and then upgrade to 2.0.14 upwards. (2.0.14 also uses some of the new features from 2.3)
But 2.2.x will still be supported with bug fixes and security updates if required, so stick with it if you are happy with it.