I would not bet against Swanwick airspace being controlled from France.
This wouldn't be wise from the French.
Staffing:
We already feel a beginning of under staffing. Not sure we could deal with any more sector before 5 or 6 years, as every other controller leaving on retirement is not replaced and we don't see many newbies coming...
FAB:
Since France signed the FABEC agreements, UK is not in the same FAB. Agreements should be changed first (before they fade away).
Communications:
Safe data links are dealt with by numerous private telecommunication companies. These companies have no aviation culture at all.
Some failures I've witnessed in latest years, on so-called "safe" lines, spring to my mind.
We've got recurrent problems with our radio antennas in Spain (which should be solved soon), there has been a major disruption with Shanwick, some with UK...
As long as these incidents imply only a loss of time in co-ordinations, so be it...
It would be quite another problem if that means a total loss of radar informations, or frequency/CPDLC.
To save more money and avoid new investments, I've heard radar data will soon transit via the internet, instead of our own (really) safe intranet !
I hope I'll be far-far away before we control Swanwick from France !
PS : Anyway, who would train us on these sectors ?