They have little reason to suck it up and pay these taxes. It's easy to book of shore 'profits' and with an occational tax holiday there is huge incentive to do so. Just create a a 'paperclip' in an offshore company and bill the US company 1billion for it and you get to avoid paying taxes what joy. Then wait a few years and bring that money home on a semi regular holiday.

PS: Or we could say on Dec 31 there will be a one time 50% tax on any money in offshore accounts and you can clean up this mess real quick with them quickly moving all that money back home.