I honestly do not get what's your problem. We moved from 4.8 to 7 because a) the better compiler warnings helped to reduce the amount of shit people where able

I honestly do not get what's your problem. We moved from 4.8 to 7 because a) the better compiler warnings helped to reduce the amount of shit people where able to check-in AND highlight problems in the existing codebase (beyond "well, it looks like written by the lowest bidder offshore guy drunken on Friday night") and provide management with metrics they could understand (two warnings per LOC is part of your problem). B) it deepened our hiring pool, because it's easier to find people willing to work with current technologies than legacy. C) it allowed us to pull in various modern libraries (BLe especially) which made whole swathes of swamp code irrelevant. D) allowed us to establish a sane Ci/CD Pipeline more easily which we needed to reject bad stuff. F) we ship this product every few months, so not being on lts is not really a problem.