I certainly hope so The A350-900/1000 is a joy to fly on and in my experience makes a difference when on it versus the 77W. Currently, the CX S24 timetable lists the following for LHR, but this is provisional, and is as you mention still to be confirmed (e.g. flight times haven't yet been adjusted to reflect the longer routing due to the Russian airspace closure):

CX251/252 77W
CX257/238 359
CX255/250 359
CX237/256 359
CX253/254 359

As mentioned, these are merely provisional, and I would expect more, if not all of the above A350-900 sectors to be reverted back to the 77W. Someone on Flyertalk mentioned that the London route is a priority for Cathay to introduce the new Aria suite product on all flights. Given this, I reckon there is a slim chance we will see the A350 return to LHR on a permanent basis sadly. More likely to see it back at LGW if this route is reopened.