I think the only question over Vx future is whether PSA get rid of the brand altogether, or rebrand their products with VX badges for the UK market.
getting rid of the brands altogether is the only justifiable reason that PSA bought it in the first place.
It would have been cheaper to not buy it, and let the brands disappear on their own.
I suspect PSA will utilise the brands (though maybe remove Vauxhall and just use Opel) to target different customers. Or keep Vauxhall and use it as a global budget brand, and sit Opel slightly above, keeping their home brands as premium - Pug more traditional, Citroen more hip.
I agree with MigV6 in that there has been nothing remotely interesting new out of Vauxhall/Opel this millennium, what with the dull Vectra-C and is equally dull (but better to drive) successor. The Astra/Corsa type cars will always have a market for young families and 2nd cars, or for those where the family has flown the nest.
Vauxhall/Opel's dullness does really match what set in at Peugeot from around the mid nineties, and Ford around 10 years earlier - though in Fords case, I think they are changing in the last few years, and making cars that are more rewarding to drive. Hopefully that's some hope for other makers to follow...
But the fact remains, the vast majority of buyers aren't even remotely interested in driving.