I think by the end of this year we will see a drop in prices on the T5 version only as prices are way too close at the moment, if you could get a T6 for an extra few grand you would strtetch yourself rather than buy a T5. I think autumn time will be when prices stabalise.
It's possible, however over the long term we may see the T5 prices staying reasonably firm and instead find that the price that you would end up paying for a T6 rising considerably. There are several factors that may cause this to happen:
1. There is already talk of a forthcoming VW price rise.
2. The new VED changes coming into force next spring will add considerable cost to buying and running a new Cali.
3. It has been said on this forum that dealers are quickly using up their allocation of new T6 Calis. If this is true and VW don't increase production then dealers will almost certainly decide to either reduce or stop offering discounts. Why would they if stock becomes difficult to source.
4. The current incentives to buy a VW following the emissions scandal, (e.g cheap extended warrantees, servicing deals and loyalty bonus etc) may be gradually phased out as the issue becomes history. VW now needs to save money somewhere, lots of it!
5. The pound may be affected by the EU referendum result and we may end up paying more to buy new cars.
Points 1 and 2 will happen. Point 3 and 4 may happen and point 5, well who knows? But my conclusion is that the cost of buying and owning a new T6 is going to continue to rise and very probably quite steeply. If this happens then I cannot see the prices of second hand vehicles rapidly dropping.