Would it be totally impractical for all or most Met journeys to/from
Chesham
to run as through services to Baker Street as opposed to mainly a branch
shuttle with the odd peak-time run to Aldgate or wherever. Just seems a
bit
messy compared to most other lines which tend to provide through services
to
all their extremities.

It would be possible but I doubt enough people use Chesham off-peak to make
it worthwhile.

But equally anyone from Amersham would surely use Chiltern. If anyone
used Chesham at all, a better off-peak pattern might be making the LU
Fast trains Cheshams.

Also would it not be feasible for Central Line trains serving Hainault to
run alternately clockwise/anticlockwise round the Hainault loop and back
towards the City?

As there would be no terminus there would be nowhere for the trains to make
up any time and this would decrease reliability.

What might be a better idea would be to make all trains via Newbury
Park terminate at Hainault and send a few trains an hour to Hainault
via Woodford. This might finally do something about the abysmal
ridership at Roding Valley.

Are there any changes to traditional route options on LU that might be
worth
doing even if the above two are hopeless non-starters?

I believe LU are considering changing the sub-surface lines. Trains would go
Hammersmith - Edgware Road - Liverpool Street - South Kensington - Edgware
Road where it would reverse and head back the other way. This would have the
advantage of giving Circle trains somewhere to make up any time they have
lost.

This is a stupid idea. It would just end up sharing terminal platforms
with the Edgware Rd District, so the amount of recovery time available
would be necessarily tiny. The route would effectively become
Hammersmith to Hammersmith with a reversing move in the middle. On
time performance towards Hammersmith would be appalling, unless an
extra wait were added at Aldgate, which rather defeats the point of
the whole exercise.

A better plan might be to replace the Circle with a Wimbledon -
Wimbledon Loop, or alternatively to run Hammersmith - Aldgate -
Wimbledon and Wimbledon - Edgware Rd - Whitechapel.