Sure, there has been very little reason to take out an adjustable rate mortgage when you can lock in a historically low rate which has been the case the last couple of years. However ARMs were one of the things that caused the market to collapse in 2008 and as rates tick back up over time it's likely that they could become an attractive option again. The other thing is that at some point people need to sell and what is barely affordable to so many now at 3% will surely become unobtainable for many more when rates are 7 or 8%. At some point doesn't it turn into a mobility crisis as there's less and less people who can afford to buy.