Classic 4* heros will stay relevant for quite some time. Some places longer other places less depending where you look.
Yes you are right the top 4/80+15+ heros will be hard to fight with classic 4* heros.
What did we expect? They are top of the line 5* heros with a huuuuuge investment of symbpls to top it off.
Still…top classic support 4*'s lmaxed out with symbols will still play a role.
Think Rigard, Kiril, Boldtusk, Sabina, Melendor, Cademon, Soja, Grimm, Tiburtus et al.
Titans and wars:
Since these are dependent on alliance you are fighting with they will still be a mainstay for a long time to come.
With the introduction of symbols it was obvious that for a short time the 4*'s will close the gap and the the gap will start geting wider again. We are now in the geting wider again phase.
At the end of the day I am still the top scorer in my alliance most of the time although I have only 5 maxed 5* heros but around 40 maxed 4* heros and my defense defenitely is not the strongest any more. sigh
I stay in low diamond with that roster although I noted my defence starts throwing away cups in huge amounts again after I improved it with Joon about a month ago. Sartana is in her last ascencion and should replace Elakanen soon.
So yes fighting against loaded 5* is geting harder but that was to be expected and is no reason, that the classic 4*'s should become obsolete in the near future.
Hope you all pull a lot of 5*'s and all the mats to ascend them!