I think putting quotes around 'tablets' was really the way to go, actually. I think at this point, what we call these things is slightly a bit off anyway. We're trying to call something which does more than make phone calls a phone by throwing the word 'smart' in front of it to make 'smartphone' -- and calling anything bigger a tablet, but now we have the form factors meeting up somewhere in the middle around 5-7". It's really all the same thing now except for one little thing -- the one thing that's left, other than size (which IMO is meaningless now), that really distinguishes a "phone" from a "tablet" --- the appearance of a line item on your bill that says "voice."
What happens when we're all using Skype/Facetime/VoIP for all of our calls? Moving toward that trend, at some point, when we're all using VoIP to make a regular calls, the one remaining vestige of "voice service" will probably be the ability to make a reliable and instantly traceable 911 call. It won't be called voice service anymore since we'll all be using VoIP for our calls, we'd only be using their "voice" service for emergency services. So it'll end up being called "emergency services" on our bill.
So at that point, will we distinguish between a "phone" and a "tablet" based on whether you can call 911 on it?
I think we should just call them all PDAs with different sizes for different purposes, small, medium, large, grande, venti, whatever.
Personally, I don't care about the items on my bill: I draw the line between devices I can use like a handset and devices that are too large for that. Devices in the first category are "phones" everything else isn't.
The reason why I think the distinction makes sense is that there are too many use cases where a "phone" is the best solution, either because of privacy, convenience or social acceptance. Just to make an example, video calling has been around for a long time now, and yet I don't think I've ever seen it used in the wild. Things may change in a generation or two, but for the time being there's still a place for devices that are mainly phones and can occasionally make do for other stuff.