It’s been four days since AT&T (T) announced the wireless pricing changes that go into effect on Monday June 7, and opinions about what they mean vary widely. The responses we’ve seen fall into five basic categories. Let’s count them:

1. A classic bait and switch. AT&T signed up millions of Apple (AAPL) customers — first on the iPhone, then on the iPad 3G — with the promise of a $30 all-you-can-drink data plan. That’s gone now for new customers, replaced by what AT&T calls DataPro — $25/month for 2 gigabytes plus $10 for every additional GB. Existing customers are grandfathered in, but there’s no guarantee that won’t change when their contracts expire.
2. An attack on the bandwidth hogs. According to AT&T, only 2% of its users draw more than 2 gigabytes per month and they’re clogging up the network for the other 98%. You can tell who the data hogs are; they’re the guys who have been squealing the loudest. By forcing them to pay for the bandwidth they use, AT&T will either drive them away (relieving some of the stress on its network) or turn them into a new revenue stream.
3. A sweet deal for the rest of us. In a note issued late Thursday, Katy Huberty reminded clients of a Morgan Stanley survey that suggested Apple could increase demand for its iPhone by about 40% with either a $50 cut in the price of the phone or a $20 drop in the cost of the service plan. Next week, we may get a bit of both. With its entry level DataPlus plan ($15/mos. for 200 megabytes) AT&T has cut costs by $15 for the 65% of customers who use less than the 200MB limit. If, as expected, Apple reduces the cost of the iPhone 3GS from $199 to $99, that’s a $100 price cut on the hardware side. If Huberty is right, sales should explode.
4. A gift to its competitors. If AT&T’s decision is as boneheaded as many of the comments here suggest, Verizon (VZ), Sprint (S), and T-Mobile (DT) should be able to sweep up a ton of new customers. If you thought Verizon’s “There’s a map for that” ads were effective, wait until you see its next campaign.
5. Just the first shoe to drop. To hear AT&T tell it, the days of all-you-can-drink pricing are over. They made sense when the carriers were trying to attract customers with what looked like a free lunch. But wireless bandwidth is an increasingly scarce commodity, and all the U.S. carriers — like their counterparts overseas — will soon be forced to switch to metered pricing.

P.S. Nobody likes the $20 AT&T is charging for tethering. Since customers are already paying for whatever extra bandwidth they use, it feels like double dipping.

See also:

• AT&T pulls the plug on unlimited iPads

[Follow Philip Elmer-DeWitt on Twitter @philiped]