I dont know much about the buisness end of things.
If you are expecting to replace an income like that, then a serious look at the business end of things will be crucial. Relative to all the other tasks involved with a brewpub, making the beer is easy. This is in no small part due to the fact that it's the fun part. As others have said, marketing is key, and the day to day grind of how to run a business is also very important.
My wife and I have been running a small winery in Missouri for over 11 years now. All along I've been saying that my plans are to add beer to our list of offerings. That concept is only recently getting closer to reality. My initial thoughts were to just offer draft in our salesroom, filling a niche that we know exists. However, the closer we get to putting this faction of our business in place, the more requests we receive for a bottled or kegged product. Fortunately, at the same time we are also seeing a bit of interest from potential investors, so this could get out of hand real easily.
I guess my point is that you can take this in just about any direction you'd like. So far, I've read two books on startup breweries:
Beer School by Steve Hindey and Tom Potter of Brooklyn Brewery
and
Brewing up a Business by Sam Calagione of Dogfish Head
These two plans were quite separate in both philosophy and starting/operating capital. Both ended up with some serious backers that not only diverted disaster, but also allowed timely growth. But they still don't encompass the full range possible for brewery operation.
The prime example of a minimalist operation was a small brewery near Willow Springs, Missouri called "Little Yeoman Brewery". An older gentlemen bonded his garage and started bottling batches from carboys, five gallons at a time. I did not have a chance to ever visit his place (heard he recently sold it, which is the best way to make money with a brewery!), but quite a few of my friends/customers (that line blurs rather quickly, especially when they bring me beer) had brought me assorted six packs of what the old guy was brewing. They all had character, without screaming flaws; they were bottle conditioned; and the labels looked like they were printed straight off of a desktop printer. I can only imagine that he was retired, and was not seeking a 40k income from his operation, but the point is that you can start at any level. You don't have to jump right into a fern bar microbrewery with millions of op dollars.
Our brewery will most likely be somewhere between Little Yeoman and Dogfish Head. With the groundswell we've received from potential investors, I could picture it expanding even further and faster, even though we haven't quite taken on opening an escrow account. Nothing is quite as tell tale as when you actually ask for that check!
So keep asking questions, including those that address your heart. A properly done business plan will help tremendously with finding both the questions and answers necessary.
You have actually already posed one of the more important questions, "just how much revenue do I need to see". This is exactly how I've operated our winery, which is quite a different game as the inventory has to be produced on an annual basis with annual forecasts. For me, without actually getting started, beer is already looking much easier:
- higher profit margin (for brewpub in our situation; pre-existing
salesroom, no bottle inventory, no distribution, no bottling equipment required)
- inventory is readily renewed
- materials are readily available.
Anyway, good luck with your dreams..... as luck may be one of the more important ingredients.