Nothing to do with 2G / 3G networks
For the slightly confused about it.
The 4G rollout should have no effect what so ever on the existing 2G or 3G networks in terms of 'fixing them'. 4G is a totally different infrastructure. Telco's are 'fixing 2G/3G' by replacing it with 4G.
Its not just about speed, its about contention. The existing 3G network is plenty fast enough, its just that there is an exponentially large number of people using it now, and there isn't any more space in the frequency to cram more people into it. The 3G network is the '3 lane M4'. The 4G network is a 25 lane M4, its just got a lot more capacity.
Also the network edge doesn't dtop off. See those 2 bars you've got on 3G? They have a massive impact on your network handshake. Same case on 4G, no impact at all, its full signal to the edge of the network handoff zone.
Next thing you'll see is that 3G goes altogether. 2G will become m2m (Machine to machine - i.e. your washing machine / boiler / eleccy meter) and 4G will be THE data network.
So thats how they'll fix 2G.....