Last update January 20, 2022
Short answer is NO
If you used VST2 version of a plug-in until a point and now want to switch to VST3 format you need to be aware that in order to open older projects (featuring VST2 format) you need to keep the VST2 version of the plug-in installed as well. This is result of the approach we've taken to deal with VST.
VST2 and VST3 formats of D16 plug-ins aren't interchangable. Meaning both formats coexist in a system side by side as separate plug-ins. So if you want start using VST3 format, you need to finish all the projects using VST2 and start new ones using VST3. Having installed both plug-in formats in your system. That will give you time to migrate.
This approach; meaning being able to use VST2 and VST3 side by side is approach taken by many companies, since replacing VST2 by VST3 is supported properly (to our knowlege) only by Steinberg in Cubase. Most DAWs cannot do that.
VST2 is still, and will be supported by host application developers. Also Steinberg will continue to support VST2 (using VST2 plug-ins in their DAW) in upcoming versions of Cubase on Windows and on macOS (Intel builds).