Don't get me wrong, I agree that WHM is currently the weakest of the three healers overall, but unless you are relying on a balance card to meet a DPS check or skip a mechanic, a well played WHM most certainly isn't going to hold a group back in any current content with or without echo.
Assuming potencies don't change wildly, WHM stands to gain the most from the removal of standing dancing and accuracy by a healthy margin IMHO. Assize is going to be incredible in 4.0, Fluid Aura will be consistent free DPS and Aero 3 resists will be little more than a horrible memory thank god. My main concern with WHM for 4.0 is that SE won't address the MP deficit it faces compared to AST and SCH. Beyond that, if Omega starts throwing J-Storm style aoes at us, you can bet your bottom dollar that WHMs quickly start finding favour again.
And yet I still see PFs for A12s that lock out DRK and AST which never fails to give me a giggle.
I'll add, I've seen this all before, you'd see people proclaiming that WHM was useless in Turn 5 yet I was healing for one of the top EU progression FCs at the time and we always ran WHM/SCH (Primarily because we could reliably time our cures to land between death sentence and infirmity). It was also amusing to watch how BLMs fell out of favour in SCOB and then promptly bounced right back in FCOB primarily due to the content favouring a particular job over the other.