A few people have asked this via my eBay listings. Nothing lasts forever and of course one day the 2g signals that have been running 3 or so decades will be switched off.
We’re in a slightly better situation in the United Kingdom though. Unlike Australia (who switched off their 2g signal) and America (who plan to) in the uk we have a rather unique geographical layout that necessitates continuing 2G signal for operators to maintain their coverage % as high as possible. There is also the growth of M2M application where smart appliances for example use that part of the spectrum to operate. This is a growth area too.
So long story short… we’re good for a few years yet. Don’t write off your old handsets just yet.
More info here: