I've seen kits sold at Bass Pro Shop, which makes no sense at all.
But as far as the craft beer upswing, my thinking has always been this: breweries will become like restaurants. The big boys will continue to dominate in sales numbers like fast food chains do. Larger craft breweries (Sam Adams, Sierra Nevada, Stone, etc) will have a large nation/international presence as well similar to Red Lobster, PF Changs, etc. Then there will be regional and local breweries just like you see a small restaurant around the corner from you that is family owned. Since the capital investment and operating costs are greater for a brewery compared to a restaurant, we aren't talking about 200 local breweries for a large metro area like Houston, but instead it could maintain 10 or so comfortably.
What we will see an end to is small breweries becoming national companies regularly. Those starting a brewery now should not aim to be the next Sierra Nevada or Ballast Point, they should aim to become a stable for their region at most. Unless you are lucky enough to have a large financial backer and a lot of connections such as Karbach here in Houston (make great beer, but you can tell that their owners had connections in distribution by the way they were able to grow so quickly).
Look at a place like Germany. I would assume there are approximately 1,300 breweries for about 80 million people. Compare that to about 1,600 breweries (not including brewpubs) in the USA for almost 300 million people. Many of the small breweries in Germany are dedicated to a small local region. I worked at one during college over the summer that really only served about a 30 mile radius (it is also the one my grandfather and great-grandfather worked at; Stolz in Isny).
Another way to put it is this: when someone starts a restaurant, they don't think they will become huge. They normally think that they will create a nice income for their family and enjoy their work. People used to (and still sometimes do) start breweries thinking they will own a big business eventually. That mindset will most likely change over time to fit more of the restaurant model.
The other side of your question is demand; will the demand for craft beer keep up? I would say somewhat. Already you are seeing the shift from IPA's to sours and saisons. Stone used to get by just by being the bitter bastard, but is now being forced to look at different styles. But that's the beauty, there are so many different styles that it will likely become a cycle of what is hot right now. On top of that, while IPA's are no longer the hottest thing right now, there is still a massive demand for them. They are now a staple, you can't have a brewery without an IPA in your line up. The overall demand will most likely stay stable (once it tops out, it is still growing now).
The analogy to martinis doesn't quite work either; people don't really go home and drink a martini, or make a martini to watch a game, they are more for going out and for more special occasions. Beer on the other hand is something people grab when they just want something good to drink, you keep a sixer in the fridge just in case (or in our case, a keg in the keezer and a few cases in the closet).
The total demand for beer rarely drops, and the demand for craft is still growing (you are also seeing the way the big boys are buying up craft breweries, they see the trend and want to profit off of it). To borrow from my grandfather "people will always drink beer"; if times are good, they want to celebrate, but even when times are bad, beer is still on the shopping list (just maybe not that $30 bomber of barrel aged sour saison).
Phew. Sorry. This is something I have spent too much time thinking about.
TL
R - The market is changing; breweries will become more local and regional, but with the big boys still holding the majority of the volume. Demand will not drop, but instead it is diversifying.
