I understand the argument "Anderson is doing well, so he should stay and there isn't anyone else good enough" but that is not how team sports work. If you don't retire, you get retired and Anderson has been part of England teams that have failed to grow because they are going with the same old tactics, all the while, young bowlers who could be good, never get to ply their trade for more than a test or two at a time. At some point, the ECB has to make a choice, do they want to build for the future or do they want to be stuck in the same old rut. Plus, Jimmy's numbers are insanely inflated with home tests.
He gets to pick and choose when and where and how often he plays. In the last 2 years, England have played 12 home tests, Jimmy has been in 11 of those. It's not as if he's actually blasted through at an average of 21 or something, he has taken wickets averaging almost 30...coinciding with a humiliating series loss against India. His away number are 8 out of 14 tests and the average is actually spectacular, but again, the context, he only played 2 of the 4 tests and got to play when he felt most ready.
I am of the school that successful teams are built on successful sacrifice, Imran khan built a great side by putting some older players out to pasture, including his own cousin, when their were younger alternatives available. Maybe they don't come in and set the world on fire straight away, but they get the time and experience to grow. I'd rather younger players coming through and being given the chance to fail and learn then trying the same old tricks and continuously losing.