Would a professional ASIC-machine holder eventually become a bank-like character? As we know, one of the concepts of Bitcoin is to be "decentralized". When individual miners, even with ASIC miners, become unprofitable, will the system become more centralized to those several superb professional miners? 

Would that finally affect the willingness of users to accept Bitcoin and lead to its collapse?
Even if mining becomes more centralized, it would seem unlikely that miners would turn into banks: Their only advantage at shaping payments is that they may delay transactions by not including them in the block, so there doesn't seem a direct incentive to progress to banking.

On the other hand, payment processors and bank-like entities would have an incentive to foster mining efforts, as their business concept directly profits from a secure network.

So, banks should be interesting in paying for mining, but not vice versa.