If the dealers don't make the bike a priority, they aren't going to sell. Michael Baker at Royal Enfield of Fort Worth did a great job his first year with the mark selling 60+ bikes (I don't remember the final number, maybe around 80). He used internet sales, attended vintage bike rallies across the state, and sponsored events at his location to showcase the bikes; so it can be done.
With that said, the US isn't a prime market for the Royal Enfield because the power and performance don't meet the expectations of the American motorcycle consumer. Regardless of how well the Royal Enfield is built and how reliable the UCE engine is compared with its predecessor, American riders typically want a bike with more power. I think the plan I saw for Royal Enfield targeting emerging markets in Africa and South America is brilliant. The gas prices are higher the roads are typically smaller and their are a lot of people that would appreciate the UCE 350 and 500s.
If RE brings out a twin, it might have a real chance in the US especially if gas prices continue to rise. However, bang for the buck wise, Honda's new CB500F twin is listed in the $6,000+ range, has 44hp, a large dealer network, a reputation for reliability, and is available with ABS. In a head to head comparison all Royal Enfield has in its favor is classic styling, which unfortunately doesn't appeal to every buyer and keeps it a niche market bike.