Parroting NN Taleb: absence of evidence is not evidence of absence. Haven't we learned from coronavirus that we need to use the precautionary principle in the face of new information that is not fully understood. I don't know where you are from, but I locally heard a string of "there is no evidence of" starting in about January of 2019. There was no evidence that the virus would leave China (it did). No evidence that shutting down travel from infected areas would help (see Vietnam). No evidence of community transmission (it has happened in most of the globe). No evidence that masks help prevent transmission (appears to reduce transmission rates).
I am starting to think as soon as someone asserts "there is no evidence" for something related to the coronavirus, it is a foregone conclusion.
In any case, nobody can assert with absolute certainty that the coronavirus cannot mutate into a more severe or more transmissible virus, especially in the face of a the long human history of being (literally) plagued by mutating viruses.
A critical mutation is a possibility and we should be extremely cautious and vigilant against it. Even if we erroneously overreact 10 times to false mutations, the 11th time might be the one the matters. And the cost of those 11 overreactions will be much less than the cost of letting it go wild.