I agree it doesn't pass the sniff test (where are the 500 meter trees in the rainforests?) but I think it would make an excellent goal for molecularbiological and genetic engineering. We (our civilization) need to become much more skilled at that before we start editing the human germline, and we will inevitably want to edit the human germline eventually (or rather we are currently exhibiting great restraint in not doing so but I'm not sure how much longer that will last), and anyway thousand meter trees just sound like they would be really cool.
There are obviously other factors limiting tree growth, like compressive strength.
> 500m
500ft is taller than the max ever, not 1640 ft
Sounds cool but for such experimentation you would want relatively fast experimental iterations to get anywhere, and this would take literal ages. You can play around with growth speed of course but that’s a different question and might be in some ways opposed to achieving height.