We don't allow speculation about house prices on askaboutmoney, but in any event, people can't predict house prices.
You are making a profit before charges of €12,000 per year on an investment of 470k. Depending on your actual costs, rent-free periods, maintenance, etc., this looks like a good return. It is only a good return though, because you have such a cheap tracker.
This is a return of 2% on the capital employed. If you keep the house for 10 years, you will have a cumulative return of around 20%. If house prices fall by 20% over the next ten years, you will still break even. Your guess is as good as mine or as anyone else's.
I think you should approach BoSI and ask them will they do a deal if you sell your house? This is costing them a fortune. They may offer a discount of around 10%. This would be worth taking, although you should start out by asking for more.
Where are you living now? Will you want to buy a house again in the near future? If so, then you should sell as banks will be reluctant to lend to you if you have a mortgage already, even if it is a very profitable one.