The bull market came earlier than in 2015, so we cant predict how long will be the current cycle. It could end in 2020 or 2022, despite the halving.
Lol, this is bullshit talk. When the price of Bitcoin would go from like $200 to $400 in a few days, nobody ever called it a "bull cycle", let alone a "3 YEAR BULL CYCLE". People called the market exactly what it was back then, a Chinese pump and dump scam that can implode at any second. Nobody ever made these retarded claims pretending imaginary, valueless tokens in a pump and dump scam are somehow 'guaranteed' a THREE YEAR bull cycle. The thought is just laughable.
Bitcoin HAS NO PRICE FLOOR. The bottom can drop out at any second. It's happened too many times to count. As soon as it happens, miners shut off turning it into a feedback loop to plummet the synthetic price floor even more. Cost of production in Bitcoin is recursive based on it's own demand. It's a self-referencing system. Cost of production in metals IS NOT recursive. If zero people wanted to buy gold tomorrow, the cost of production would still be the same. That's not how Bitcoin works.
There isn't any such thing as a price floor without artificial intervention. There have been many attempts to create such a thing but none have ever worked without government enforcement.
Your statement about gold is unbelievably unintelligent. If no one want to buy gold the price of gold would plunge until there were people willing to buy it. In fact that has happened many times with gold and other metals! While gold has physical uses, those simple don't support the highly inflated value currently assigned to it. Besides it doesn't matter if something is useful is no one wants to use it or buy it.
Look at the value of your silver! It was more valuable decades ago than it is now. The value depends on buyers and sellers, not on physical vs non-physical.
While you are correct that there is a price that could at least temporary cripple BTC and probably cause demand to decease more because of lack of transactions, that is something that can be adjusted. Miners just need to be able to pay for the cost of mining. It isn't a complete doom, just a major setback. Gold on the other hand is absolutely doomed in the long term because there is just too much of it. Right now supply is limited, unlimited supply will doom the value of it no matter how useful it is. It will have value but just a tiny fraction of what it currently has.