Consider a jubilee date occurring in N years. The result would be that nobody is willing to lend with a maturity of more than N years. This is rather problematic as it means that primary debt markets can't function when N approaches zero. It would make it impossible for me to get a mortgage if N=5 for example, locking me unfairly out of the housing market for half a decade, artificially depressing house prices until N=0 when suddenly five years of pent up demand causes a demand spike/bubble.

I also don't agree that a jubilee date won't increase rates. The default risk is simply much higher now and therefore the rates must go up to compensate for the added risk. In the current system, debt isn't forgiven when repayments are late, which allows for lower rates since the default risk is lower. If late repayments automatically implies default due to the jubilee date, then rates must be higher.

Most people would be unable to get a mortgage if you were closer to the 49 year mark than not.