Thats an excellent point.
The banks are currently restricted by their own cost of funding and their need to fund their legacy loss-making tracker mortgage book, meaning that the interest rate margin is widening all the time. We saw the best example of that recently when the banks were raising their variable rate on the same day that the ECB announced an interest rate decrease. The variable rate mortgage holders are subsidising the loss making trackers, plain and simple.
I think there is a great opportunity for a strong European bank to come in and to offer reasonable mortgage rates to "positive equity" variable mortgage holders.
I think its only a matter of when, not IF.