Nobody would buy a standalone PDA these days, mainly because they'd need one core feature: Access to e-mail. At that point, you need, at the very least, a WiFi

Nobody would buy a standalone PDA these days, mainly because they'd need one core feature: Access to e-mail. At that point, you need, at the very least, a WiFi connection, but customers would likely expect a cellular connection. And at that point, bam, you have a phone. You could try to make it "not a phone" by removing the speaker and microphone, but people will occasionally want to play a game, so you'll need the speaker, and someone might want to record speech for note-taking, so you'll need the microphone. TBH, I'm not sure how you could possibly make a "not a phone" PDA. Nobody would buy an offline PDA. At least, not enough people to pay for the development of it.