Well this is just daft frankly. When the improvement works are finished and there is a smaller terminus section, no doubt the argument will be that hardly anyone uses the London Bridge - Forest Hill service so that can go too.
I do find that if travelling to most places apart from London Bridge itself, it is quicker to go Overground and change at Canada Water. It is more expensive though.
However, the loss of the ability to change at London Bridge when travelling to or returning from CX is plain irritating and I agree with Tinkerbell this makes a late night return a hassle. This will also cause massive disruption at CX in the evening peak. If anything goes wrong that station soon fills up and you can't even get in it, and that is *with* the ability to change at London Bridge.
I think that the root issue here is that Southern use the terminus at London Bridge and South Eastern seem to have monopolised Charing Cross. This is like a return to LBSC and SECR operations a century ago!
If half our London Bridge trains went to Charing Cross instead, now that would be an interesting compromise... yes, some other services might have to do likewise but there may be some interest now with this proposal.