Sorry to burst your bubble, but there probably won’t be another SU for HS (never say never).Thank you for your reply Mark!
The time of 2 months makes a HUGE difference to me because it means I'll be able to keep using my Mac Mini mid2011 for an extra 2 months if High Sierra will continue to receive security updates until November 2020.
So your Mac will be no different now or in 2 or 6 months time.
I really don’t know what your so worried about though.
You can keep using it, with common sense browsing.