It appears that it depends on your login
(and most likely disables the “Old version – Reporting” after a certain # of logins)
If you use GA alot, then it will eventually time out disabling the old version reporting located on the bottom (which takes you right back to the new version instead)
I discovered this as I tried different logins , some of which disabled the old version “Old version – Reporting” (ones I frequent more) and some which still enabled me to still use the old version of GA.
As of testing, it didn’t appear to be related to cookies, which means its coming from Google Analytics login’s itself.
If anyone has any further details about this issue, please comment on your findings below