So why does it contain clauses to prohibit people from taking out or renewing existing private coverage?
I've been slowly reading through the bill and haven't come across this yet at all. I've seen clauses that prohibit private coverage that does not meet the minimum standards of healthcare (which I haven't gotten to yet). Basically, it looks like this (so far I've only covered 100 pages or so):
(1) The 'public option': a government-run healthcare plan with different package levels (bronze, silver, gold, and platinum) that is available strictly through the 'Health Insurance Exchange' gateway. It'll be (for practical purposes here) like any other plan offered through this HIE.
(2) The HIE gateway is a virtual shopping mall of health plans that private companies can jump in on. A company must offer the basic 'bronze' package (they use other terms for the package levels, but I'm sticking with metal). Every company that offers this package will offer the exact same thing; the differences here will be (potentially) {a} cost and {b} in-network/out-of-network offerings (§114 IIRC). Companies can offer the better levels in succession (i.e. they can't offer the platinum without the others first). Platinum-level packages have the added bonus of offering optional benefits (free basket woven underwater after the fifth child born, whatever). Lastly, all plans offered through this HIE are urged to use copayments instead of coinsurance (i.e. everything is a set amount rather than a percentage). The out-of-pocket deductible for any plan here is limited to $5,000 for an individual and $10,000 for a family.
(3) Private insurance companies can also offer plans outside of the HIE as long as they meet the bronze-level requirements (§121).
There's some more details and such that I've run through, but it doesn't look like any of it relates to these options in any significant way. But don't worry, there's some potentially bad things in the bill as well, especially for insurance companies (e.g. basically there is a set limit to how much they can profit annually).