9.0 received one further maintenance update after 9.5 released - but all this did was backport some bug fixes from 9.5. It was released in the March after the 9.5 release.
There is no guarantee Steinberg will follow their historic practice. If there is a further 10.0 release, I expect it will be version 10.0.60 and am all but certain it will not contain any new features, just high priority fixes from 10.5 that are easily backportable.
If you are already on 10.0 then the upgrade to 10.5 is not particularly expensive. You can continue to run 10.0 once you have upgraded to a 10.5 licence - indeed, you can have multiple versions of Cubase installed on the same machine. The upgrade to Padshop 2 (for Cubase Pro and Artist users) alone might justify the cost if you have any use for that instrument.
Unless you are short of money at the moment, the only reason I can think of to hold back from a 10.5 upgrade is if you do not meet the much stricter operating system requirements for 10.5 (the only OSes officially supported are Windows 10 x64 1709 and 1803, also OS X 10.14 or 10.15). Some success has been reported with older OSes, but there is no guarantee things will work properly.