There are several reasons why the old left — right political framing is gone.
When there is increased complexity on many areas like economic inequality, religion, education, health etc. then the parties who favored international (but democratic) socialism are decoupling from statistical data as money prices, the Brexit spectacle would happen sooner or later.
There would also be immigration controversies, and these conflicts are to some extent different by sub category but the main factor is who or what is imported/migrated and the local level of controversy not only by increased economic inequality but race, religion, education, health, crime etc.
The new progressive real Left movement equivalence will be citizenship-ism. By definition this is that rights, positive or negative rights are assigned by citizenship to the nation state not delegated to international agreements.