In Dutch the word "miljard" for 10^9 is too well known and deeply ingrained to change I think, but with "triljoen" which could either mean 10^18 or a direct conversion from the American English trillion, all bets are off

Yeah, I too think that's likely the direction we're heading, and I'd be fine with either option as long as it was consistently used, this transitional phase is just painful.

In the meanwhile you can say one thousand millions (for what Americans call a billion), like the local tv news does, and for the bigger one say just say millions of millions (what Americans call a trillion), that should be unambiguous enough.