In all honesty, I think that the 4% guideline (it was never a "rule") deserves some scrutiny. If your bare bones core expenses add up to 4% of all your investments, I think you are skating too close to the edge. In order to comfortably retire, having your core expenses between 2 and 3 % is more realistic. You can be at 4% with all your expenses, assuming you have the ability to cut if needed. The longevity factor should not come into play, unless you are planning on spending your money down to zero. In my projections, the value of my investments goes up over time, so more time actually means more money, not less. Therefore, I see longevity as a solution, not a problem.
The low real interest rates are a challenge if you want fixed interest rate investments. But if you live on dividends from stocks, I don't think that is a huge problem. Interest rates are rising, but so is inflation. What matters is real interest rates, not the nominal rates.