I have the bandwidth to download but when my PS4 arrives next week i'll be sticking with disc based games.
Although downloading is more convenient, there isn't the price advantage from what I can see so you'll be left shelling out full price for a game you can't trade in.
I don't tend to hoard a huge game collection on consoles, once i've completed the game or worn out the multiplayer then it gets traded in towards a new game. I don't think I had more than 5 disc based games at any one time during the last console generation and was quite happy with that system.
If downloading was cheaper, say £25-30 per game rather than £40-45 or whatever it is on the next gen consoles, I would forego the trade in value and download. I haven't bought a physical PC game in years, but then again PC pricing is different and combined with the steam sales it makes perfect sense to download on that platform.