The question you need to ask yourself is, why would a bank be pitching you this product at this time? The obvious answer is that bankers believe rates will rise in the future. Getting you out of a fixed loan and into a variable one helps ensure profitability on your account.
Expanding your menu (as a lender) to include as many loan choices means you get a better opportunity to scour borrowers out of niche markets.
If you re-extend from 15 years back out to 30 years, that might reduce your monthly payment by 30 percent, ... If there isn't a likelihood that you'll pay off your mortgage, the re-extension of the term of your loan could measurably improve your cash flow.