The point here is that as soon as your usage becomes significant in any one department, there is a solution to it
already.
If you spend a few months each year in BongoBongoLand, you buy a local SIM. I am sure every Brit with more than half a brain, living in Spain (OK perhaps not too many of those
) is already doing just that, so the drop in roaming charges for Spain will make little difference.
If you use a lot of GPRS data,
in the UK, you buy a Voda badged GPRS card whose SIM card will be set up for £3.06/MB UK and £9+ abroad.
If you use a lot of GPRS data,
abroad, you buy a GPRS card and stick in a Virgin SIM which is billed at £5/MB UK and abroad.
If you send thousands of texts you can get a package for that.
Heavy users have loads of contract options.
If you are often in range of wifi then you can use Skype, etc.
Etc.
We will never see an all-round cheap solution to everything in GSM because there is no way, ever, that the mobile companies are suddenly going to walk away from the countless billions they make.