A savvy real estate investor understands that mortgage interest rates are a neutral effect.  In either a low or high interest environment, an investor can take advantage of the situation.  

Lower rates keep an investor’s expenses down, but also increase vacancies (better homebuyer affordability, less renters) and drive values up (more expensive  and more difficult to buy in hot competitive market).

With higher rates rental demand will increase (more customers for the real estate investor) and help cool down a competitive buying market (I am sure a lot of investors will agree, some relief would be welcome).

One great way to mitigate the bumps in the road is to invest for the long-term.  Whatever happens to property values in between will not matter, because you do not position yourself for an exit strategy that forces you to sell in unfavourable situations.  Run the business like a squirrel, collect the ‘nuts’ (your great cashflow due to low rates and high rental demand) during high season and store them for use in the low season.   Savvy real estate investors expect cycles, are prepared for it and do not invest solely on speculation.

Over the long-term the mortgage gets paid down by your tenants, even if there is no massive appreciation, you still win.  Looking at the big picture, you still own a piece of real estate at the end, one of the most desirable assets in the world.