An N-reg needs to be owned by a US citizen (or some other options; I think a green card holder is ok) and if he dies then the aircraft registration is invalid.
This is why upmarket hardware has individual trust companies where 75% of the share capital is owned by several US lawyers and 25% by you. That also meets the requirement, and if one of the lawyers kicks the bucket they just stick another one in there. If
you kick the bucket, you don't care anyway, but the reg is legit because the ownership is now 100% US
so the plane can be flown, sold, etc.
The only downside of the US trust stuff is that - the way the trust is normally worded - while the trustee cannot stop you enjoying the aircraft, he could (if bloody minded) stop you selling it.
In the past, some trusts gave you a pre-signed bill of sale (which in effect can be used to kill the trust
by you and the trustee cannot stop you) at the outset but fairly predictably this renders the trust void and this was confirmed by an FAA lawyer I went to a while ago. The FAA said they had a good relationship with SAC and are entirely happy with their trusts etc. Obviously they would not give names of trust companies whom they didn't like...