That's the point of securitization, which is the point of the article. The banks aren't holding the mortgage. They immediately sell it off to some other financial institution who wants to buy what basically amounts to a homeowner bond that pays the prevailing interest rate. (There are some differences mentioned elsewhere in this thread, notably that the homeowner has an option to pre-pay, there's collateral that the mortgage holder can foreclose on, risk profiles are different for homeowners than corporations, etc.)

The bank doesn't care what interest rates are going to be next year, because they sell the mortgage now and collect the cash for it. The buyer cares, but the buyer is probably a hedge, pension, or sovereign wealth fund that in theory at least should be able to estimate & offset interest rate risk.

I wish the article went into more detail about exactly who the losers are in this system. I suspect that it's essentially a policy by the U.S. government to increase social stability (in the form of homeownership, stable residence, investment in communities) at the expense of holders of U.S. dollars and dollar-denominated assets (i.e. most of the rest of the world). In other words, it's transferring wealth from non-citizens in exchange for keeping citizens happy, which is a pretty typical government play. It also looks like the system is on the verge of collapsing, in the sense that it pumps up house prices and encourages artificially low interest rates and high inflation, and hence an increasing number of American renters are being caught on the wrong side of the equation.