I'd like to stay conservative and say there's a 50/50 chance it reaches 1billion market cap.
If it doesn't reach that market cap, it won't be because of a lack of groundbreaking technological/economical advances made by the product. It will be because average Joe is too dumb to even realize the current financial system is flawed, and our inability as a community to make this product accessible to the masses.
I think what makes the 1 billion market cap possible/plausible is the focus of marketing on getting average Joe to use bitUSD just because it has more advantages than regular USD. Remmitances will also increase adoption, but won't have much network effect on the masses.
And when 1 billion is reached, if everything is properly aligned, network effect will take over. Getting the 1st billion in market cap will be the hardest (and longest) part imo.
It's like all self made millionaires say: Getting your first million dollar is the hardest part. Afterwards getting more millions is much easier --- Same here with market cap, but in billions.