Usually when a company “deprecates” a standard, it can still be used independently of the company’s authority. However, this is not the case with VST2. As of October 2018, Steinberg has stopped issuing licenses for the proprietary standard.
Anyone who has acquired a license prior may continue using the standard for now, but the distribution of new VST2 plugins is legally dubious at this point. Whether or not VST3 offers any features over VST2 is irrelevant.
This especially hurts open source and/or individual plugin developers who would not want to risk getting sued for creating new VST2 plugins. Today VST3 is more widely supported than it ever was, including but not limited to Reaper, FL Studio, Bitwig Studio, and even Ableton Live, which seemed like they would never support it.
I suggest and hope with all sincerity that the Renoise team will strongly consider supporting VST3 this time. (And/or LV2)