Dialysis extends human life relatively indefinitely. Source: On dialysis.
But it does take up a lot of my time, for one. I'm on dialysis for 4h15m three days per week. And there is a small risk every time I ahve dialysis, because it involves sticking me for two lines (output and input) and the small chance of some sort of problem with the machine (they clean them every time, but reality doesn't care if something goes wrong - it's pretty darn rare, but rare things happen).
Transplants aren't a perfect solution. You must take a bunch of pills and if you miss a single does, the body starts rejecting the kidney, and the whole process lowers your immune system becasue that's what the drugs are having to do in the first place to not reject the kidney.
So this is all good news (article), but it still ain't great.