How many devices will Apple want to sell you?

The other day I did a post on MIDs, which as with a number of my posts gets syndicated on SeekingAlpha. Leaving aside the usual rants by Apple-ists thinking I'm somehow anti-iPhone (I'm not - I even bought one for my father), the comments have raised an interesting point in my mind.

Some people think that the iPhone is an example of a MID - and that it will absorb the future capabilities of a whole range of other devices.

But other people think that the iPod Touch is an example of a MID - and that it (or perhaps a slightly larger version) will absorb the capabilities.......

So here's a question - will Apple try and structure its product line so people end up buying two devices from the company, or just one? (plus ideally a PC as well). I don't mean the serious fans who'll buy everything - I mean normal customers.

Will the iPhone be the uber-smartphone, sensible to hold to your ear to make calls, but with a good web experience as well.... while the Touch becomes a larger, different beast - perhaps a PSP-replacement, or Netbook-alternative, with ergonomics optimised for these purposes? (and with a bigger battery and screen).

I'm pretty sure that Nokia has long welcomed the trend of people to buy and carry multiple phones - why sell people one product when you could sell them two or three? It will be interesting to see how Apple organises its portfolio around this opportunity.