It's going to be a messy period while trying to establish deckbox-based pricing, but there is no reason it can't happen.
To be honest, I'm surprised at the number of people who were relying directly on TCGPlayer prices blindly for their trades or sales. They provided multiple data points in the form of low, mid, and high, and there were often large discrepancies between the reliability of these prices, especially for small-value cards.
All it takes for deckbox to get its own pricing system in place is a bit of sales data. Sellers should be pricing cards at their own prices, based on what they want to receive for their card (whether they prefer to get this information based on other retail sites, tcgplayer, ebay, amazon, their LGS, etc is up to them). Over time more sellers will have more cards available, and more sales will occur. In order to provide maximum pricing data to buyers and traders, deckbox would do well to include any of the following data:
- Most recent sold price
- Average sold price (last [1/7/30] days)
- Volume sold in last [1/7/30] days
- Lowest sold price in last [] days
- Highest sold price in last [] days
- Average volume available on deckbox marketplace in last [] days
With even a small volume of transactions on any individual card, with enough of these types of data points, it is easy to see a ballpark for what people are willing to pay for a card, and that range will get more precise over time.