Well, we do have such a procedure for such situations -- using the walkaround bottles when that's the only O2 available, and it is needed. OTOH, I have not had a rapid decompression in an airliner yet, either as a pilot or SLF.
Indeed, there is lots of room for "serious contemplation" if one suddenly finds the pilots' O2 depleted, but an immediate descent would likely add more problems rather than resolving any. Proximity to divert airports with reasonable weather would be a primary consideration. However, even with a subsequent decompression, running out of fuel is NOT a viable option!
Over the Atlantic there is little need for communication, except for position reports and declaring the emergency. Hopefully all the callbacks to Dispatch were already made when the O2 problem was initially discovered, so the options in case of decompression would have been discussed at that time. Inside-the-cockpit comm may not be ideal, but it is possible. And, the fact is that you will be flying SOMEWHERE for some amount of time, so you're committed to make the best of it.