2020 years that will be btc price and difficult same what is nowadays will be same profitable if more low profitable will be ?
Mining will likely retain the same profitability virtually forever. When price goes down, less people mine and difficulty goes down to meet this. If price goes up, people jump on board and diff goes up. It is too competitive of a market at this point. Even when no more coins are "mined", the theory is that BTC will be valued high enough that the transaction fees alone will make it worth mining.
BTC is really really young as far as what it is. We have yet to see a lot of it's potential. The top quote from toqchista2 was one of his many spam's if you read it mentions same difficulty... but we should stop quoting that.
We really don't even know what will happen at next having with price, home miners, etc. So there is no feasible way we can have a good idea of what year 2020 holds for BTC.