Questions about using Dolphin version = 7.1.5

Hi, currently im using Boonex Dolphin version 7.1.5

While Dolphin 7.x will be supported and maintained until December 2023, Boonex highly recommend all new projects to start with UNA CMS.

What exactly will happen to my dolphin version 7.1.5 when 2023 starting?
- Will my system shutdown?
- Will it no longer be possible to install independently developed modules?
- What restrictions await me ?

I wish that I can simply continue with the version I am currently using for the next 20 years. 

Nothing will happen. Boonex simply won't be providing any further updates or new versions but your site will continue to function normally.