I don't, excluding live football or highlights, watch live TV, but I still pay my license fee. I do download a fair few Radio 4 and 5 podcasts, that, for me, justify the expense. To raise more revenue, I'd have no issue with product placement being used and even limited adverts during prime time/popular shows.
Even though I don't watch, I do feel they should have a certain amount of programming that isn't commercially viable on the other channels. Educational programs and documentaries which I believe are BBC4's remit. I'd also conisder watching TV if they showcased comedy talent, going around comedy clubs in the UK and also something similar to Richard Herring's Leicester square podcast, though it would need cleaning up a tad. I remember they had the comedy roadshow on BBC1, but that was so mainstream and safe, I'd want something a bit more raw.
Plus get the rights to the The Bill and start a new show and work on the iPlayer, some stuff is not up anywhere near long enough or easy to search for. Also get more of their radio programmes released as podcasts.