Will ASIC miners hold the network "hostage" and demand a fee for their services? I can see a trend coming where miners will likely hold the network "hostage" by mining blocks with no transactions in them... even when the block reward nears zero. This would leave transactions in the perpetual pending state.

The reason I suspect this will happen is so that miners will need to cover the expense of hardware that will never be recuperated otherwise.

This scenario can also happen if the value of BTC drops to a very low value.

I'd like to understand the variables that would cause a miner, a mining pool, or anything that would cause them to demand a transaction fee in order to accept the transaction.

Question


What ratios, statistics, or variables are useful in tracking what the miners will demand the transaction fee to be?


Some ideas would likely include


Quantity of transactions -vs- fee paid  (the higher the fee, the fewer transactions will be conducted... supply/demand)
Network difficulty "beta"  (a beta is a Finance term discussing rate-of-change)
Blocks that accept no-fee-transactions vs blocks without
Transaction delay time (before being included in a block)
average miner investment in hardware
The 'race to the bottom' is still continuing in the mining market and hopefully will continue. If any of the miners tweaks transcation inclusion like you suggest that would make them less competitive in this market.

The miners have pretty much no power to enforce transcation fees while the market is functioning as intended, so your question is somewhat moot. 
If the miners do hold the network hostage that would be a sign that a cartel has formed and the mining/fee market has broken down.

If that happens it may well be that the users and developers will augment the protocol such that the miners are once more 'held hostage' by market forces.

The difficulty evolution is often described as 'difficulty follows price', this does not model the cheapening of the hardware but otherwise describes the market forces pretty well (by assuming that block rewards and fees won't change rapidly).