I'm not concerned about keeping Leo and leoJS in sync. Why? Because leoJS will track Leo but not the reverse.
Félix has already demonstrated admirable dedication to keeping leoJS in sync with Leo. I do not doubt that he will continue to do so.
Otoh, it's not possible to keep up with vs-code's development. On the contrary, that's why I am so excited about leoJS!
Summary
There is no need (and no way) for Leo to emulate leoJS.
Leo's development will likely slow or stop after I am gone, so Félix will have little trouble tracking Leo.
Edward