[nfnaaron]

Open Twitter, allow anyone to be a Twitter server, and sell their services to Twitter providers who don't want to deal with Twitter nuts and bolts, as Disqus does for comments and Google does for gapps.

Be an expert in Twitter and sell training to implementers and users, as GitHub does for git.

Have free and paid levels, as GitHub, Disqus, Dropbox and countless others do.

Have all paid services, as old school businesses do.

There's probably more else that I haven't covered.

[brown9-2]

What type of paid services could Twitter conceivably sell?

What type of paid services would people conceivably want to buy from Twitter?

[nfnaaron]

Cooler Twitter. Enterprise Twitter. Better Personal Twitter management.

"What possibly" and "conceivably" assumes that the current form of Twitter is all it could ever be.

If they're smart enough to do Twitter, they're smart enough to enhance Twitter in a way that people will pay for it.

Keep in mind, this is all based on the linked article's characterization of Twitter as an ad company, and what they might do instead.

[axod]

Twitter T-Shirts, Twitter mugs. Twitter fail whale plush toy.

I'm joking by the way.

[thetrumanshow]

Why, the Twitter service itself. Its called lock-in.

Rewrite the licensing to say for non-commercial use only, except under special license. Allow businesses to opt into a licensing agreement for a few hundred bucks a year. Release the hounds on any unlicensed companies.

[Maro]

Remember that Twitter has a certain 'scale' in terms of expenses (employees, servers, etc) and in terms of VC invested so far. So bussiness models that generate less revenue than required by this scale are not acceptable to them (their investors).