Say the year is 2140 and miners are no longer receiving block rewards, only Tx fees. How do we know that these Tx fees will always make mining a profitable endeavor? Especially considering that block sizes are currently hard-coded and we don't know the impact of second-layer solutions?

Will something need to change in the meantime to guarantee this? For instance, a blocksize scaling mechanism that ensures that there is suitable demand for block space? Or will the users slowly take network security into their own hands and run distributed and/or embedded miners to decentralize the currency and not care whether or not the mining is profitable?

What happens if we develop a technology that provides everyone with unlimited free energy? Do we 'globalize' bitcoin?

It's questions like these that make me really trust the long-term prospects of PoS more than PoW, since we can continue to use self-interest and greed to improve the network indefinitely without needing to be cognizant of large-scale changes in how society functions.

Maybe this is more of a philosophical discussion.

It would be great if we could provide each other with watch scripts that can be used to modify mining intensity in response to popular programs.

For instance, if you are a madVR user:

Code:

      <watch condition="RunningApplication" action="Stop">
        <conditionParams>
          <process>madHcCtrl</process>
        </conditionParams>
      </watch>

or a bf3/origin game player:

Code:

      <watch condition="RunningApplication" action="Stop">
        <conditionParams>
          <process>GameOverlayUI</process>
        </conditionParams>
      </watch>

In essence, what processes correspond with common programs that require modifying mining intensity?