Do you mean viable as in commercially viable?
I've had some good ideas on how to write a "magical school" rpg, complete with scaling things based on maturity level much like the HP books did. But you're probably right, I'd be aiming it at young adults and I don't think that even my best idea in the hands of the biggest gaming company would be commercially viable given the likely costs of obtaining the license.
Might make a good indie game for me to put together someday, though.
I don't want to hijack the thread but since you asked I'll bite.
For sure it would not be realistic for Green Ronin (or pretty much any other RPG company) to pull off a financially viable Harry Potter RPG. I don't even know if WOtC could pull it off (we had the HP TCG and that didn't last too long). I feel the need to cover myself and say I am speculating and using an educated guess on financials.
1) Cost. HP is a mega brand and will cost a lot of money to license. I would guess it would require a 15% royalty with a minimum $100,000 a year royalty guarantee and possible minimum marketing spend. My guess is a company may be in hole for $750,000 in sunk costs before you've shipped book one (pre-marketing spend).
2) Approvals. When WOTC did the TCG Warner Brothers managed the property very closely and had a very tight style guide and brand bible. With any property managed like this it would be difficult for an RPG company to have the latitude to make an RPG that was open enough to give players ability to author their own stories and make the game their own. RPGs need a big world for people to play in or give players the tools to add to the world themselves. I don't think HP offers either of these options.
3) The property. These are great stories with magic, monsters, and colorful characters but because of #2 it is not likely to be a deep enough world to make for good roleplaying. It especially doesn't have the depth to capture the current table top RPG audieince beyond a passing curiosity so this would need to be a younger skewing RPG.
4) Audience. Because the primary fan base for HP licensed toys and games skews young (6-12 YO), to launch a pen and paper RPG based on the property you'll have to be in the big box stores (WalMart, TRU, Target, etc) as well as the book trade. To do this launch right and have enough marketing to drive awareness you need to tie it to a movie release (capture the halo effect from other licensees and the movie hype). This means you'll be spending a lot of money on marketing. My guess is it will require a $5 million dollar spend with a 1 month window of opportunity before your game is headed for the markdown bin (AKA DOA).
So in conclusion, no I don't think HP would be a viable RPG.
Dark Tower on the other hand has a ton of depth. I think it would make a great RPG setting because it has an interesting mix of sci-fi, Arthurian legend, old west, post apocalyptic futurism, fantasy, and real world. The band of gunslingers have been to multiple locales, worlds, time periods and there is tons of room to expand the world in a points of light type of treatment. You could have many classes and great
NPCs. One of my favorite NPCs is the psychic vampire
Dandelo who feeds of the emotions of it's victims.
