There are loans marketed as interest only, but my understanding is that even with these loans the payment of the capital is deferred to the end of the term, not that you don't have to pay it back at all.
There are annuities, a financial instrument where the seller receives a lump sum and then pays back a fixed amount in perpetuity but I think only insurance companies sell these.
I think the most likely scheme is what the other comment is suggesting, refinancing the loan repeatedly