Two of the largest risks of having tests is that they will not be run or even pass. This is what will happen if you have a test suite without experienced developers maintaining it. In this case, it will no longer bring value, but only baggage. A test suite that is not used and doesn't pass is a waste and should either be fixed or deleted.

I was once working on quite an advanced order flow. To maintain its quality by myself, I covered the solution with tests knowing that if my tests were green, the code would work as expected.

I handed over the code to a maintenance team and after six months, they called me up asking me to fix the code. They were going to make some changes, and when they did, the price calculation no longer matched up. "So, are the tests passing?" I asked them. It turned out the developers had inactivated the test suite when the first test turned red.

It is easy to avoid this by having continuous integration run the tests every time code is committed to...