Legally, if you filled out a KYC for these exchanges, couldn't your wife get what you have on the exchanges at least, through legal means?
Yes, if you left it on the exchanges. But then you are left with the problem of trusting the exchanges to hold your funds -> not the ideal.
I guess that's better than simply dying and taking the coins with you. I mean coming from the US, if the exchange is involved here, I'm sure by law they would have to accept the procedure. If they deny it they will get in huge trouble.