I think what you are missing here is what is the novel part of my idea and what is the conventional. It is not novel to think of an attenuated vaccine, what is novel is to look for an attenuated strain in a pandemic using genome sequencing. I hope someone else has thought of this, but so far I haven’t seen any evidence of this.
Waiting for vaccine is not a good option. This is a situation with only hard choices.
To assess the diversity and spread of the virus it appears. To the best of my knowledge nobody is systematically looking for a natural attenuated strain by genome sequencing. If you are then please get in contact with me.
"Waiting for a vaccine" is mostly a strawman. We're being asked to wait 2-3 months for the outbreaks to reach a size where they can be contained by testing, tracing and quarantine. But that only works if people take this seriously and honor the lockdowns.
Even if this would work in rich countries, this is not a realistic option for people in poor countries. They do not have the money to wait in isolation for the next 3 months.
We’re also likely to see convalescent sera available shortly, and neutralizing antibodies available in several months. Those, along with more widely available testing, will help us tread water until we develop a good drug or vaccine.
Waiting for vaccine is not a good option. This is a situation with only hard choices.