Since no one here is working for US Soccer, it's impossible to know for sure, if he's seriously on their radar or not.
Team US has two friendlies in March against Chile & Ecuador.
The US coach could just do a Hudson, and look to 'cap tie' Boyd in either game. I'm not sure how that then works for Boyd if he is capped in a friendly by the US, I presume he can't then jump back to the AWs later on? ie just the one national team allegiance change in a career?
Obviously be very disappointing if that happened, Boyd's far more valuable to NZ, than the USA.
But the AWs have done it plenty of times (well grabbed age group internationals from other nations), so glasshouses and stones.
Yep, you can only switch once, so that would be that.