My reasoning:
* Each transaction in Bitcoin costs hundreds of time more than a credit card transaction to process. (currently this is subsidized by inflow of capital into the eco-system, so users haven't felt the full effect).
* Hundreds of millions of dollars are paid to mining hardware vendor and electricity company. This will continue year after year, and only will grow more and more as Bitcoin grows bigger. The Bitcoin community is being bled dry. The price action this year shows that even with massive amount of big name adoption and good news, the inflow of capital is having trouble to keep up with the insane surge of mining cost.
* There are better ways to secure the network, for example Bitshares's DPoS system. Money is re-invested into the eco-system and community, instead of paid to hardware vendor and electric company.
* If Bitcoin doesn't drop PoW and embrace the much more efficient DPoS system. I can see Bitshares eventually overtake Bitcoin. Simply because Bitcoin eco-system is bleeding hundreds of millions of dollars each year, and the DPoS re-invests the money and grows the eco-system/community each year.
Btw, you can hold BTC in Bitshares
1) I'm assuming you're including the block reward as part of the transaction "cost". That's not a valid comparison, since that is money injected into the network. Even if it was, upon reduction to negligibility of the block reward, that number will drop dramatically. The free market will eventually settle on what makes a fair transaction cost is in absence of a block reward.
2) So hundreds of millions of dollars is better paid to people who hoard Bitcoins? Won't PoS this only increase the problem of hoarding? And honestly, I don't care if miners have to sell 100% of their coins to make a buck. So be it - the market will settle on an appropriate price for Bitcoin with the increase of Bitcoin supply on the exchanges, and that will be that. There's no such thing as "The Bitcoin community is being bled dry", as you would like to suggest. The price is being held down, perhaps, but is that the only stick with which we should measure success? To me, it is an excellent thing, because a lower price means a better distribution of Bitcoins among people. More people holding Bitcoin = better long term success of Bitcoin. PoS would encourage fewer people to hold Bitcoin (because fewer people would want to sell) = lower long term success.
3) I disagree, for the reasons listed in #2.
4) If Bitshares proves itself to be a better system, then so be it. The free market will decide. I don't see any reason to fork Bitcoin away from what it is not to match another system that already exists. Let each system with its unique variables stand on its own, and we'll see which is the better system simply by watching what the free market decides.