You're currently in the process of walling up your garden of API-awesome. All of this is happening because you need to earn money. You are about to kick the very thing that made you great. And continuing on that course, you'll lose in the long-run. Before getting to the idea, let me point out where you stand.
Have you ever considered the reasons anyone would be using Twitter over one of your competitors? Have you ever gotten the impression that "merely" serving as the central point of information exchange is the thing you're great at? I'm not using your website much. I've switched from using Twitter.app to Tweetbot. Not because I hate Twitter, but because they simply do the job of interfacing with a user - namely me - on a much better level.
I'm not using any of your clients, but I still claim to be tweeting. I still tell people I'm on Twitter. I still identify with your platform.
Why is that? Probably because you're the central and very integral part of this whole 140-character communication-sharade I've come to love.
Wow, this must be a big revolutionary thing, nobody has ever thought of, right? No! In fact it's dead simple. Having figured out that you, dear @twitter, are an API-Service, you should be thinking about monetizing that API.
I'm currently thinking about throwing $50 down app.net's throat. I'm willing to pay for service. The service I'm willing to pay for is not some limited Web UI or some iOS app. It's the communication infrastructure behind all that. And that, let me repeat myself, is what you are (to me).
Offer (quite) limited API-access to everyone for free. Then offer paid API-access for more bandwith or features. You can identfiy my user account. Since I have to authorize every app I want to use in conjunction with Twitter, you can identify them, too. Now, if I'm a paying user, simply allow the apps I've granted access to the better API-service I've paid for. How could that be any problem?
Please realize that I'm willing to pay for your API-service only. I'm not interested in your apps. I will pay others for allowing me to use their superior user interfaces. That said, I don't hate your software, I just find others did a better job than you. Accept that. Take my money. Rule the world.
At the moment I'm really looking at alternatives I would use in a post-Twitter era. Should you, however, get your shit together, I'd be more than happy to upgrade from Twitter User to Twitter Customer.
Various discussions on Twitter are based on the assumption of me thinking Twitter is on the way of sinking their ship. I do not think that is the case, per se.
I'm a web developer and the bulk of people I follow (and who follow me) are developers, too. We're a niche. A specific clientele. A flock living on the internet, mostly because it's where we work. We are not the average Twitter or Facebook users. We have different expectations. I'm pretty sure the average Twitter user is perfectly happy with how things are turning out. Let's not kid ourselves - in the grand scheme of things we are a minority.
For that very reason I do not believe Twitter will fail and die any time soon. Especially not after being tightly integrated into iOS and OS X.
What will (actually "might") happen is our niche moving on to different services. After all, we are the people capable of creating these services in the first place. We don't use tools we don't like. We rather create our own tools than using something that doesn't seem right. (Look at our open source world and you'll understand what I mean…)
Also I do not believe that Twitter hasn't thought of my "great idea" long before this post. I suppose they did and have found enough reasons to not pursue a paid service. I'm very clear on the fact that this post will move exactly nothing, except maybe put the thoughts of so many fellow developers into words the internet would have not seen otherwise.
The actual question still unanswered is: Where will we move to? Is it app.net? I have no clue. I'm not eager to jump ship. I will do so at the last reasonable moment.