"As the network operates now, you host a node if you want to sell a product, buy a product, or be a notary. If you aren't doing those things, there's no point in hosting a node, it doesn't help the network at all. Since you cannot buy, sell, or notarize without hosting a node, then being able to do those things is incentive enough." -- http://www.reddit.com/r/OpenBazaar/comments/2i1cxi/incentives_to_host_nodes/ckyn7ea
Plus there are some other things such as needing to download and connect to all the other sellers - from what I read this takes a fairly long time and likely even longer over Tor, plus it might result in higher security issues. While vendors and buyers are pretty tech savvy, are they so tech savvy that they would dare host a node (for possibly long periods of times, connecting to many peers) as opposed to just jumping onto TAILS, and using a multisig "centralized" marketplace?
I guess we will see but I also have my doubts.
I'd say it won't be picked up because there are easier and quicker alternatives.
Most people don't really understand the difference between a P2P and a centralized market, can't see why is it more secure or why would it need to be more secure since they are never going to get caught anyway (the mindset of a drug dealer or buyer).
For most people "a P2P multisig decentralized market is more secure" sounds like the same as "We at market X keep you safe". Since they don't understand how these things works, they just rely on a promise in both cases and will take the easier, quicker way and go with the flock.
Just as with multisig.