To answer the original question, yes the game can be completely free to play.
Practically all aspects of the game, including expansion and quest packs, in game features, etc., can be purchased with Turbine Points. Turbine Points can be acquired without limit through game play. You can get TP on different servers and different characters, and they are pooled together. Expansion and quest packs need only be purchased once and apply to all characters on all servers.
So if you create (and, if necessary delete and recreate) enough characters on enough servers and play enough time, you can have enough TP for anything in the store.
That being said, your gameplay experience won't be as good as if you started out buying the expansions and becoming VIP. Swift travel is (for me) the most important feature I miss when I'm not VIP. There are probably others, but most things VIPs get can be bought with TP.
I started and played almost 6 months as f2p, and still have f2p accounts for crafting alts that I use with no trouble. But my time is worth something, so after spending a few hundred hours playing, I decided it was worth it to become VIP. I don't spend many TP on other things, so I've saved enough monthly TP being VIP to buy HD.
I spend more on drinks and snacks consumed while playing than I do on the game itself. The great thing is that you can get well into the game to see if you like it before you have to spend money. Later, you can decide based on your playing style how much to invest (in grinding time or cash) in the game.