you never should turn off mining devices if you want them to be profitable 
second high quality miners are very hard to get and cost alot as well
difficulty is the tool which slows down the blocks being made when more power is added, it actually was designed for cpu usage
so if it had only be used by cpu's it would have a very long time before the blocks would be mined even if the whole world would have been mining them.
But it all went into gpu / fpga and now the asic storm which makes it faster and faster with less power.
So the difficulty is constant being adjusted upwards by the btc mechanic to compensate the enormous power being added
The difficulty will slow down the speed in which blocks are found a little bit, but it still leaps behind the massive power being added each week.
Even now we know many companies are still in the proces of delivering machines ordered in 2013 (cointerra, bitmine, bfl) and some are busy with developing even faster ones with even more power (knc)
So your main problem will be gettting new hardware capable enough to make enough coins so they make enough in a short time frame to compensate the loss of the initial investment.
For example a cointerra costs $6000 but will be only available in june/july ... many months later then you acutally want...
Almost every company selling rigs is still using the pre-order scheme so buy and instant delivery is almost impossible.
So many things to consider and to work out.
second high quality miners are very hard to get and cost alot as well
difficulty is the tool which slows down the blocks being made when more power is added, it actually was designed for cpu usage
so if it had only be used by cpu's it would have a very long time before the blocks would be mined even if the whole world would have been mining them.
But it all went into gpu / fpga and now the asic storm which makes it faster and faster with less power.
So the difficulty is constant being adjusted upwards by the btc mechanic to compensate the enormous power being added
The difficulty will slow down the speed in which blocks are found a little bit, but it still leaps behind the massive power being added each week.
Even now we know many companies are still in the proces of delivering machines ordered in 2013 (cointerra, bitmine, bfl) and some are busy with developing even faster ones with even more power (knc)
So your main problem will be gettting new hardware capable enough to make enough coins so they make enough in a short time frame to compensate the loss of the initial investment.
For example a cointerra costs $6000 but will be only available in june/july ... many months later then you acutally want...
Almost every company selling rigs is still using the pre-order scheme so buy and instant delivery is almost impossible.
So many things to consider and to work out.