Technology will cause miners to become more efficient in terms of energy consumption. As of now miners are becoming more efficient at a faster rate then block rewards are halving.
a larger number of TX's per second will eventually be a possibility. This will likely happen when then is some kind of economic incentive to host a full node.
Technology already hit a cap on ASIC mining.
None of the miner will really have any incentive to have their miners running to confirm transaction soon.
Less efficient mining machine will shut off. And less efficient mining companies such as hashfast and cointerra will disappear.
The hashrate of the less efficient machines is much less then the more efficient machines. In general the vast majority of the new miners brought online are more efficient machines. Look at how fast the network has grown, only this year. Late last year the difficulty was well under 1 billion, and in 6 days the difficulty is estimated to increase by ~1.4 Billion to ~13.1 billion. In other words the network is growing every two weeks at a rate that is faster then the entire network late last year.