A lot of suggestions have just been posted and several of them deal with ads, basic accounts, sponsored accounts, etc. and/or account levels in general, the basic idea being how LJ can continue generating revenue and keep their users/keep their users happy.
In other words
suggestions is waiting for your 2 cents. :)
ETA:
foxfirefey kindly provided links!
Basic accounts suggestion About new Sponsored accounts Basic accounts and Paid users Basic accounts Keeping basic ad-free accounts, without losing much ad revenue Refunds Possible Feature for Permanent Account Holders?