a) Wearing my business owner hat I don't see that your product managers will be able to split up the work in effective ways to deliver business value early without having an in-depth understanding of our business. I don't know of anybody who outsources product management.
b) Wearing my developer hat a major part of my skill set is the conversation you have with product owners about the work they want done, the value they want out of it, the alternatives available, etc. The original request for X can rapidly transform into Y with a bit of Z. By cutting the developer out of the loop with the product owner I'm likely to deliver less value for time spent.
c) Anybody who has worked with large distributed teams on product development knows that communication and integration is hard. This model would seem to be adding in extra layers that will only make it harder. There isn't a team - there's a bunch of separate developers who's reward is tied to their piece of functionality rather than the product.
... so colour me unconvinced with the model as stated.
How much of your business model relies on people converting from your website? If it is a substantial number: As part of your audience (a developer) I can divulge my first impression of your site. It is that I have no idea what your website does, and I won't give you my e-mail address to find out.
Some solutions: 1) Explain with both sufficient and few words what it is your website does. Use pictures if you need to. 2) Allow me to explore your website risk-free, or in other terms, without requiring any information of me. 3) Try further to persuade me to try your product through marketing ploys such as free things, empty promises, etc.
And the earning shares thing will have to be exact using some formulas basically, which could then lead to potential for someone to game the system and get lots of shares, which would be a problem.
I think it's a neat idea but hard to get it all to work, good luck.