I believe most of European users would be grateful for multi-currency support. And for ex-USSR countries it's an especially common practice to budget in two or even more currencies.
In fact, some people in my country have salary in US Dollars even it's not an official currency of course. Most people here think in dollars or euros even they don't plan to leave the county for next 20 years. I personally have three different savings accounts in different (!) currencies, like a lot of people in my country. So, it's rather difficult to manage my stuff with YNAB.
Actually, I thought I will never ever buy a financial software without multi-currency support... Well, YNAB was so great, I had no choice
But still hoping for a such feature.