I just had a thought that might be the equivalent of a brain fart, but...
Let's imagine this scenario:
You have a wireless network set up - a few new Macs via AirPort/Ethernet.
You have an old-school AppleTalk network set up with Macs that have no ethernet capability, just Printer Port-based PhoneNet boxes all strung together. You have no iPrint or LocalTalk to Ethernet bridges or any of these other things that are, to be fair, increasingly rare.
You get two of these AirTalk dongles. The newer Macs either don't have serial ports, or if they do, they can't use both ethernet and serial port AppleTalk at the same time.
You could hook one dongle into one of the ethernetless Macs to connect it to the wireless network...but then it would leave the PhoneNet chain, breaking its connection with the other ethernetless Macs.
The main gist of what I am getting at is this: with the way these work, and how old-school, OS 9 and older networking works, I am not sure that there would be a way to actually bridge these two networks together.
Perhaps in the future there would be some sort of way to make these dongles function as one jack of a two-jack PhoneNet adapter. That is, one side would be a phone jack for wiring into the next PhoneNet Mac, and the other "jack" would be the AirTalk adapter. This way, you could bridge both networks at the same time. I am not sure how difficult it would be to pass the signals along and make it think that AirTalk is a physical phone wire (although I assume how this works, it already does somehow).
Obviously this is like a version 2.0 thing or something....I just thought that this could A. Make it possible to blend networks using just LocalTalk cabling and wireless/ethernet, and B. not create an "odd man out" scenario as is described above for a Mac needing to pick one network modality or the other at a time.