The funny thing is, what those people are too short sighted to realize, is that if HBO veers too far off the established path Martin's writing then they'll paint themselves into a corner.... especially since the book series isn't even near finished yet.
I'm guessing any storyline changes taking place right now are due to budget and/or television time constraints and will be short and self-contained within the season (ie, without repercussions from season to season). In other words, I doubt HBO is doing anything as drastic as, say, on the level of "hey! what if we keep Ned Stark alive?" Then they'd have to write for Ned Stark in future storylines that are based on the scenario of him being long dead. I feel like HBO is still getting from Point A to Point B with the storylines, but if going down path TUV instead of XYZ means saving on budget and time (but doesn't affect Points B or C or D... etc) then I'm all for it.
Game of Thrones looks to be reaching that level of Wire/Sopranos level of public and pop culture consciousness (especially in the meme-age) that every network absolutely covets. Doing anything to seriously damage the long term prospects of the show does not fit with the author or the network, and hasn't been HBO's M.O. in the past.
I think all fans (of the show, of the books, of both) will be fine once all is said and done.
