Remortgage interest only MortgageMortgage interest only Remort Mortgage
From the top: interest-rate mortgage loans used to be child's play to obtain in the mid-2000s, but after the credit crunch creditors withdrew significantly from them. The main reason for this was that the regulations for mortgage creditors were tightened in 2014. Assuming that you would be willing to convert either part or all of the mortgage to an amortizable credit, your case would probably be considered more favourable by them.
Also, there are some who restrict the upper retirement at the end of your mortgage life to 65 years. Now there is a good selection of bausparkassen, in particular willing to loan up to the ages of 75 and even 80 in some cases, provided you can show how you can maintain your mortgage repayments at that ages.
Good mortgage brokers should be able to steer you in the right directions. Accessibility is the latchkey to any mortgage. Dependent on the affordability, you may want another pure interest mortgage, a principal repayment or even a mix - partially pure interest and partial repayment both. A pure interest mortgage has the benefit that the amount paid per month is much lower than a mortgage for repayments because you do not repay the amount you have lent.
At the end of the day, you still end up oweing exactly what you lent, while you don't owe anything for a redemption mortgage. Also because the amount you are indebted and on which you are paying interest does not decrease, you are paying more interest over the life of the mortgage. Now, if you can affordable do this, it might make sense to move to a payback mortgage or a mortgage that is part and parcel.
That would remove or at least lessen the need for a redemption mechanism to disburse the amount left at the end. Retention of a pure interest rate mortgage means that if you are saving (and not spending!) your bonuses may well be a good way to repay them; it is now a condition to have one and your creditor must be able to prove it.
Dependent on the duration of the loans, it may be that by the point at which you have to pay back the amount lent, the children have gone and you are willing to reduce the size to something smaller. You should be able to obtain a mortgage for 20 years at the tender of 50, up to a maximum of 70; longer if you can prove that you would receive a good annuity or will work after that date.
All in all, your position is not uncommon and resolvable, but it is not easy, so you would probably best talk to an independant mortgage advisor.