Yeah, there are upgrades needed to the 3rd Rail system, especially with the increase in units! Hopefully then, as you say, 92s can stretch their legs a bit further in DC land.
thing is, even if the 3rd rail could provide the amps, you’d still need last mile battery or diesel power, or at least electrify a reception road where a shunting engine could be swapped onto the consist. I’m most familiar with Eastleigh and Southampton, most of the flows to and from those places would require a Diesel engine north of Basingstoke, the only exception being possibly the Hoo - Eastleigh workings and maybe the gypsums to West Docks. Anyway, going well off track here.