This issue has been up and down ever since it was discovered on the official website months ago. Back then, all we knew was that those who purchase a physical copy of Spyro: Reignited Trilogy would have to download Spyro 2 and 3 in order to own the full package. With the delay and rumours of multiple discs, some fans were hopeful that this was no longer the case.
Activision has finally clarified the situation. According to IGN, the publisher has said that some levels from Spyro 2 and 3 will be on the disc, but that you will need to download the rest in a day one update in order to have the full games. So, for those with a physical copy who aren't connected, they'll have full access to Spyro 1, and access to some, but not all, of the second and third titles.
This still seems like an odd solution to us. Day one patches are the norm these days, but those updates don't usually have to make your purchase a complete one. We'll have to see how it all shakes out when the game launches on 13th November. What do you think? Please don't breathe fire on each other in the comments below.
Update: Here's a link to a video from Achievement Hunter, which is where the above information originally came from. The discussion about the content download is near the end of the video.