It definitely depends on the location. And it varies tremendously even within a few square miles. One of the biggest costs of opening a bar is the liquor ticket, but most states have quotas for each governing body, so it's much more expensive to get a ticket inside a city than it is to get one in the hick town just a few miles outside the limits. Unless that town is dry, of course (Ohio, f*ck you).
As for profit, if you asked me five years ago, I'd say I could easily turn half a mil into a 50K return given the right location. I'm not as sure now, simply because costs have changed so dramatically, I haven't been able to keep up. To hit that level of return, I think you'd need to see some new developments in efficiency that, while already popular in chain restaurants, would still be far in the future for local pubs.
But given the right location and proper funding, I'm confident I could put together an operation that was profitable within two years, and approached that 50K within, say, five or so. Maybe less if I got lucky with the right employees.
Edit: to give some context to how much success can swing in the business, the last bar my old boss opened, which I helped him set up, was unprofitable for the first 18 months, but within three years, it was making so much money that he was pulling out 100K a year from his capital account, while the bar's cash reserves were still growing.