It obviously cannot be a forever bullish market, especially since Bitcoin's bull runs are quite extreme. We're used to those "bubbles", but I always consider them as being a second chance to enter the market at a lower price.
As you said, I've also always known first months of years to be quite crappy for BTC. I expect a little short term consolidation soon, but overall.. I think the bull run has only just begun.
That's right. We can't expect this bull run to be forever. So at some point, it will go down. But when? No one knows. So in order to prepare for what's to come, you should have some sort of plan to optimize what's happening in the btc market.