Many of the individual crew insurance polices (surplus lines) will soon restrict ANY NATIONLITY to 180 days in USA. e.g. RESIDE BLUE from Seven Corners start this for anyone renewing after November.
'Surplus lines' plans are not 'admitted' or 'regulated' by US authorities but many have taken this new action due to Healthcare Reform.
There are excellent plans availalbe to all nationalities that do not have this restriction.