While we haven’t seen the full track, there are some images for about half the track available that can give us some idea of what is coming. Here’s a list of the rewards shown for levels 1-25 and 41-50:
- Legendary Card
- Darkmoon Faire Pack
- Darkmoon Faire Pack
- Darkmoon Faire Pack
- Epic Card
- 100g
- 100g
- Scholomance Pack
- 100g
- Cardback
- 100g
- Ashes of Outland Pack
- 100g
- 100g
- Tavern Pass
- 100g
- Year of the Dragon Pack
- 100g
- 100g
- Darkmoon Faire Pack
- 100g
- 100g
- Scholomance Pack
- 100g
- Legendary Card
…
41. 200g
42. Ashes of Outland Pack
43. 200g
44. 200g
45. 300g
46. Darkmoon Faire Pack
47. 300g
48. Year of the Dragon Pack
49. 300g
50. Hero skin
So, for the 35 levels covered by what I could find, you receive:
2 Legendary cards
1 Epic card
5 Darkmoon Faire Packs
2 Scholomance Packs
2 Ashes of Outland Packs
2 Year of the Dragon Packs
A Tavern Pass (for Arena or Duels)
A hero skin
A cardback
2700g
So it looks like cards packs may be more front-loaded in the reward track, while gold increases over time.
We still need to see how much experience is needed to go through the levels, and how fast you can get it. From the listing here, it seems like players who play pretty regularly may be expected to go a good distance past level 50 if they are intended to receive the same amount of gold as they doo currently.
The images for levels 1-20 I found through the Blizzard Press Center:
The pages for levels 21-25 and 46-50 are each briefly visible during the Hearthstone Chat video that they did for the announcement (the section about the Reward Track starts around 3:20 in the video):
Here’s the image for levels 41-45, from Out of Cards Reveal Stream post: