Tunnels (or similar solution) which are capable of taking freight off the GOBLIN and safely onto the goods lines of the MML would be potentially quite useful in the ever advancing cross London freight crisis. The Dudding Hill branch also probably has lots of potential in the future, if only as a diversionary route for WLL freight, which could head out to Kew and then get access to the WLL and MML avoiding Willesden (I think, don't quote me).
However, diverting GOBLIN services away from the Gospel Oak would be a bit of a nuisance as this is a very important interchange for the line. You're not realistically going to cram any more trains down the line.
Getting a GWML connection is also going to be a problem - I suppose you could hope that some kind of connection to the mystery Old Oak Common interchange is possible, but any kind of access to the actual main line is very optimistic.
This might be a success, given as it links to Thameslink and maybe a couple of other useful places, but it's quite unlikely and won't happen due to the fact it would cost a lot and that it doesn't serve any current central London flows usefully.