The DLR was fairly straightforward to introduce as driver because it was a bespoke system built from the ground up. I would say it's much more difficult to implement changes to systems which are already running, in many places, at capacity.
One example is the introduction of Track Circuit Block signalling on the Wherry Lines, replacing the Absolute Block semaphores. Both AB and TCB are mature technologies, the latter being the more recent, being first introduced (I think) in the 1950's. The Wherry Lines upgrade has been significantly delayed and it's generally been a load of hassle. It's an upgrade on a couple of single lines in a fairly quiet part of the railway and it's still not been delivered on schedule and within budget.
I wonder what would happen if they decided to implement ATO on the approaches to London Bridge, for example?
If the railway is still around in 2050 and we aren't being teleported or living in a post-apocalyptic wasteland, then TCB will be in place too.