I see my (supposed) alt account is very active lately. Lol.

In my opinion, it is quite easy to get merits today.
Yeah, I think the same. I'm OK with 111 merit sources, no matter if some of them don't spend their merits. There are enough merits to be distributed and merits flow, that's what's important.
If I were Theymos, I wouldn't want to put in too many merit sources either, so that everyone would have an inflated merit number.
Some merit sources usually give a minimum of 4 or 5 merits per post. I bet that if they were not merit sources they would give only 1 merit to many posts.
I guess they will be appointing some more merit sources from time to time, because some people (merit sources) will leave the forum, or they will stop being so active distributing merits, but I don't think we will need many more, and even less soon.