First we need BTC to get to a trillion market cap, which I think is definitely doable IF it becomes more easy to buy. Less KYC, more ATMs, but with governments seeing btc as a challenge, that seems unlikely. A lot of media excitement at Bitcoin breaking a 200 billion, 500 billion etc market cap could get it to a trillion.
It will likely not become easier to buy, so we need another trigger. I think a repeat of the 2008 recession could do it. Probably btc woud initially fall, but then move up. The question is how high before investors want to cash their chips in? There's a ton of people sitting on a couple of btc. If each one becomes worth 50k and the dollar is worth just a fraction less than what it it is now, a lot are going to cash out and buy houses and cars. There will be greed, but there will also be fear and its not hard for a normal person too google bitcoin spiking to 20k and quickly crashing. Getting back to that 20k would be an initial target then 50k which is a nice round media friendly number and one that is high enough that it would tempt people to cash in.
I think bitcoin needs a few years to get up to that 20k and if it happens slowly but steadily, then we can hit 50k. If everything goes well and it starts getting easier to buy and easier to spend, I think 1/2 of gold's market cap is a reasonable goal. There are other crypto currencies out there and some people will still buy gold and it would take a long time for Central Banks to transition from gold to crypto. I don't think such a thing would ever happen in our lifetimes, but they might start adding crypto to their reserves rather than selling off gold. So 3.5 trillion I think is a good next goal which takes us to roughly 175,000 per btc.
This is assuming the government/media don't start supporting a new crypto that is backed by Gold or the full faith of the US government or god knows what people might believe in. But getting back the target of 175k, I say we need around 3 years to get it back to 20k, it will probably fall back again for some period, maybe 2 years, then mass adoption, recession etc could get it to 100k by 2030, and I'm not going to bother with an estimate for doubling that.
Could it go on a massive run and spike to 20k this year? Sure, who the heck knows. But to be sustainable it would have to be supported by something, maybe if a country or two adopted it as their national currency. Something radical and unforseen. I imagine some will naysay this, but an asset currently worth almost 100 billion increasing in value by 20 times in the next decade is actually insanely optimistic. Look at stocks that started off as penny stocks, they don't keep increasing in value exponentially year after year and although btc isn't a stock, there is a limit to how valuable it can be.