So far only Peter R's idea for initial distribution based upon a *snapshot* of the Bitcoin blockchain makes sense to me (no IPO coin will ever be more than a scam in my eyes).
Bitcoin's distribution is far worse than, say, Nxt's. It makes no sense to adopt it for a new coin.
The advantage of an IPO is that the investors have a vested interest in using their initial stakes to develop the coin. It reduces bystander apathy. People don't value what they get for free. It's not the only viable way, but it works. There have been Nxt clones that had "better initial distribution" as their USP and main selling point. They sank without trace. Nxt is still going strong. Time has shown its founders are not scammers or in it for a quick profit.
Besides the initial distribution problem, you aren't addressing the "nothing at stake" flaw in POS.
It's been addressed loads of times. It's a chimera. It doesn't exist in real life. PoS has been running long enough, with high enough market cap, so demonstrate it 's secure.