Wait for More Details
The videos we've seen will help you set expectations as we push closer to the game's release. That said, some details are still missing.
We don't know if there will be DLC, something that would add replay value to a game where the single-player is the primary component. We also don't know if there will be a playable demo or a beta though at this point that seems unlikely.
Naughty Dog says it will reveal more about the game in the buildup to the release. The exact timing of those announcements is unknown.
If you're unsure about The Last of Us 2, either because of gameplay or money concerns, you might want to wait until we know more.