There will be one more release of 10.0 with some backported fixes from Cubase 10.5 as it stands then (I would expect some 10.5 bugfix releases first). However, if you want new features, you will have to pay for 10.5.
Steinberg have done alternating major/minor paid upgrades to Cubase for a while. If you don’t want to pay for 10.5, don’t. You will pay more to upgrade to 11 when that is released that someone upgrading from 10.5, though.