There is now good news. XMM-Newton is alive and well - see this October 23rd ESA News item. Should be back to observing in a few revolutions.
XMM-Newton, ESA’s X-ray observatory, has re-established communication contact with Earth, showing that the spacecraft is safe and fully under control. The news was confirmed this morning by the mission control team at ESA’s European Space Operations Centre (ESOC) in Darmstadt, Germany.
Radio contact was re-established on Wednesday 22 October around 18:00 Central European Summer Time (CEST).