We must ask ourselves, "Would it be beneficial for the big players to get in a hash rate war if the price of bitcoin remains the same or not MORE than double at the time of the block halving?"

The price of bitcoin would have to at least double to see twice the difficulty we see now.  For it to be 3x of todays difficulty, the price of bitcoin would have to be 3x what it is today for it to be beneficial to the big boys after the block halving.

There comes a point in time where it is no longer wise to invest funds into more hash rate if the rate of return does not justify such actions.  Doing so will push out the home miner for a while but certainly not during the winter months.  I know I would keep several of my rigs just for the winter months.  So, if a hardware manufacturer that mines for themselves makes a move in a hash rate war, it will not be in the winter.  It will be in the spring or early summer.  Even then, there is much risk.  They will have to acknowledge they will not have as much return during the hash rate war.  They will have to acknowledge they will not have as much return on their investment during the winter months either.

Let's say they do increase the difficulty so high it pushes out other miners.  They did this while also diminishing their own returns for a little while.  What do you think the other miners [who were pushed out] would do if the price of bitcoin rises to a level high enough to offset the difficulty increase?  They will get back in!!!!!!!  Thereby diminishing the big boys returns once again.  Which would make them wonder if the investment they made for increasing their hash rate was really worth it.  They would have to continue investing more money into more rigs to increase their hash rate even more to push out the little guys.  Also, the big boys have each other to worry about as well to make them wonder if it was really worth the investment to increase their hash rate.

So, the big boys have a LOT to think about if they wish to increase their hash rate exponentially.  It could very well back fire on them.  However, it may be a risk they are willing to take if they have enough capital sitting by for the long rainy days that will occur from such action.  Their return on investment would take much longer from such action.  If they add more hash rate after an increase in bitcoin price to push out miners who got back in the game, it would only mean more capital spent and more equipment to be concerned about making ROI.

There is definitely much to take into consideration by the big boys if they wish to get into a hash rate war.