I'm not aware of any plans to change the changeover point.

I believe the latest plan is to move the changeover to City
Thameslink. (originally it was Blackfriars)..

Farringdon, surely?

That was meant to be read that the original plan was to move the changeover
point to Blackfriars (from Farringdon), now it is planned to move it to City
Thameslink.