Presumably the way to address EO lines is to stick a couple of cabinets outside the exchange?
Yes.
They even do (or did) this on smaller exchanges without fibre services.
It really is the best/easiest place to install a new cabinet. All the copper meets there anyway. There's usually power. If no fibre for miles, there's usually ducting linking the exchange to the Head-End.
It's only useful for Exchange Only lines close enough to the exchange though.
I'm not sure how much FTTC is being installed now.
The preferred upgrade for EO lines will be FTTP if possible.
Most of the exchanges that make sense to put an FTTC cabinet outside will probably have 1 by now.