I generally keep the older version for around six months to make sure that I have means to open and modify older files in the event of issues.
On Windows, you can have V5.1, V6 and V7 plus future V7.99 side by side at an extra cost of disk space only
aaaa....ok , i understand now !!!!KiCad EDA V6 was released on the 25th.
Available for Windows, Mac and several Linux distributions
https://www.kicad.org/