Next virus after coronavirus ?

Not additional restrictions, and most likely less.  Most pandemics involve a form of the flu, and most of them don't occur in the Fourth Turning, when everything gets exaggerated.  The last really deadly pandemic - and it was a flu - was 1918.  There have been several pandemics since then, none of which caused any lockdowns or mandated masks.  Even the 1957 pandemic, which was also a flu, seems to have been pretty deadly like covid - and, like covid, killed mostly seniors and almost no children, didn't cause lockdown.  I actually remember it - I was 10.  I recall hearing on the news that 25% of school children were out sick.  But that was in the First Turning, when everybody is hopeful and confident.  
It is the political and historical phase we are in that causes these crazy reactions.

We don't know. The last proper pandemic was the Spanish flu in 1918 but there has been other more localised epidemics during that time.

Assuming a future pandemic it would depend on the actual virus.

How would we know.
Introduction of
SARS - 2003 caused restrictions in some countries
HKU1 - 2004 no
H1N1 - 2009 no
MERS - 2012 caused restrictions in some countries