For better or for worse, that is true. But I sure as hell don't want a whole movie of that.
The only way I can see this being made into 3 movie would be to have parts one and two dealing exclusively with the text of the Hobbit and have the third be based on things from the Appendices of the LOTR - namely the story of the white council ousting Sauron (the Necromancer) from Dol Guldur, his stronghold in Mirkwood.
In fact if I remember correctly the original plan was to split the two movies this way, with the Dwarves' quest being the focus of the first and the White council being the second. However that idea was abandoned in favor of intertwining the two stories because
they are happening at the same time.
As far as what happens between the things mentioned above and when Gandalf talks to Frodo at the beginning of the FOTR it's not enough to make a movie out of. However, I do think it would be cool if they included mention of the following:
- Bard rebuilding Dale.
- Gollum leaves the mountains and begins his search for the 'thief' and his ring.
- Sauron declares himself openly in Mordor - his old stronghold rebuilt.
These things would go a long way to tying the Hobbit and LOTR together nicely, and now that I think of it I really hope they are included at the end of the second movie. However, no way there is enough there to build a whole movie out of.