After finding out you live in Sherman Oaks Mistwell, I heartedly approve and hope you go through bringing us a store full of gaming goodness 
I personaly like PDFs, but I doubt any gaming company is going to go to a solely PDF format, in fact Malhavoc Press will probably produce more Hardcover products given the success of AU.
If we take the core rule books, one could possibly argue that the DMG and MM could be left in PDF form.
I frankly use the SRD to cut and past monster stats when I write adventures, but also use the MM quite a bit in game,(wandering monsters, summon spells etc).
However, you can not replace the PHB, even if you were to bring a laptop to a session, hell I dont like how people treat my PHB to look something up, imagine icky dorritos hands over your nice keyboard
Trending wise though PDFs could probably be expected to pick up more market share. This assumes continued decrease in price per page for affordable printers likely to be in peoples home, and continued increase in broadband internet connections.

I personaly like PDFs, but I doubt any gaming company is going to go to a solely PDF format, in fact Malhavoc Press will probably produce more Hardcover products given the success of AU.
If we take the core rule books, one could possibly argue that the DMG and MM could be left in PDF form.
I frankly use the SRD to cut and past monster stats when I write adventures, but also use the MM quite a bit in game,(wandering monsters, summon spells etc).
However, you can not replace the PHB, even if you were to bring a laptop to a session, hell I dont like how people treat my PHB to look something up, imagine icky dorritos hands over your nice keyboard

Trending wise though PDFs could probably be expected to pick up more market share. This assumes continued decrease in price per page for affordable printers likely to be in peoples home, and continued increase in broadband internet connections.