Seems to me Sram is abandoning mechanical shifting for road with the intro of electronic Apex. I suspect mountain (ie, flat bar) groups will be the only mechanical they do in the near future.

It will be interesting to see how Shimano respond to this. SRAM Rival pretty much forced Shimano into making 105 Di2. With Tiagra being replaced by the new mechanical CUES group, I wonder if this will leave a hole in their electronic lineup? Or are SRAM being a bit optimistic with the market for a £1300 groupset at that level?

SRAM also introduced a brand new 12sp mechanical version of Apex alongside the electronic version.
They've actually done the exact opposite of what you suspect.

Shimano has an electronic Di2 version of CUES already, though it's marketed more as an e-bike/commuter solution.

I think the new Apex is SRAM's answer to GRX. It's 1x only and seems squarely aimed at the entry level adventure/gravel market. Shimano will likely have a new/updated GRX soon (12sp mechanical was spotted at Unbound a few weeks ago). It wouldn't surprise me if Shimano released a mid-tier GRX 400/600 that is Di2 and competitive with SRAM's Apex on price.

That all makes sense thanks. I think electronic groups are still too expensive to be the only choice at 4th tier level at this point in time. But the tech is certainly starting to trickle down. I wonder how far away electronic Ekar is?