Well the Carters were blamed last year and that episode had 2m more viewers.
I actually don't think it's something you can analyse in respect of one particular programme as numbers were down across the board. EE's death warrant shouldn't be written on the basis of Christmas Day viewing itself being in decline. Emmerdale only had 4.2m.
EE's best days are obviously behind it (same is true of soap in general) and nothing lasts forever but I don't think it's on the verge of being cancelled like some claim. TV viewing has a whole has fallen and is continuing to fall. I can perhaps see an argument that poor decision-making from producers has sped up the decline but an on-going decline of notable magnitude would exist regardless in line with TV as a whole. There is so much more out there now. It's not necessarily the case that if the show's peak quality had been maintained by producers with identical visions of EE the audience would have been.
I can't see the BBC axing EastEnders while ITV are still pushing Corrie and soaps still rank highly in the viewing charts. Only a small number of programmes do better and they don't fill anywhere near the same amount of airtime. There will be reductions in episodes/budget before the axe is swung and we're a long way off even that right now.
One of the reasons I think Santer was good news for EE is that he managed to stabilise the ratings, an anomaly made even more remarkable by DSO being in full flow in his era, the increasing popularity of services like Sky + and the introduction of BBC iPlayer. I do think that is testament to his work consistently connecting with the audience at large. I know and respect that he wasn't for everyone but he can't reasonably be painted as a failure beyond personal taste. However, looking at TV as a whole now, I don't think his arresting of the decline would've held indefinitely if he'd stuck around. The general downward trajectory is rarely defied and can't be permanently.