The question isn't: "What is the next bubble?" The question is: "Which of the existing bubbles will collapse first and cause the rest of them to implode?" Furthermore, the even bigger question is: "Is there creeping contagion forming behind the scenes in derivatives and shadow banking similar to 2007, out of sight of governments and regulators yet again?"
The central banks of the world have gone on a ridiculous 8 year binge to prop up global growth, this binge will have consequences. Probably for Donald Trump, who may buy another two years of bubble activity with his planned economic actions.
Most people are used to the 1999 bubble and the 2007 bubble. Those are just the ones that got really out of control Over the last decade, numerous smaller bubbles have come and gone, mostly deflated by government (foreign or otherwise) intervention and we are generally none the wiser. China has had bubbles in their real estate and stock market come and go (or be suppressed, for now) several times in the last couple years.
If you have seen what China is willing to do to their skies in terms of pollution, imagine what they are willing to do behind closed doors in their financial and real estate sectors. One can only imagine the toxic, over-leveraged stew that is likely lurking behind the scenes. People have been expecting China to implode for years, it hasn't happened.
In the United States there are multiple bubbles now. Students loans are clearly in a bubble. It was announced this week that the government admitted to falsifying data (they call it a "technical glitch," It is not a glitch, it was likely deliberate) around what % of sub-prime students were not repaying their debts.
The private tech stock bubble of worthless, unprofitable Silicon Valley unicorns who can never go public is alarming but seems contained for now and not of a large enough size to tank the stock market.
Sub-Prime Automotive is also a bubble, but so far the numbers are far lower than anything near what was experienced in 2007.
Real estate in the United States in some segments, notably high-end real estate in Miami and Manhattan were both in bubbles as well and seem to have deflated. There was also a significant housing bubble in Vancouver which seems to be deflating due to government action.
So there are numerous bubbles that we know about. But this isn't the real problem. The real problem is that credit, derivatives and shadow banking going on behind the scenes. While many regulations have been passed to ensure that the United States banking sector is more "solid," the financiers of the world always find a way to introduce more leverage.
My conclusion after digging into the various bubbles and their sizes is as follows:
Sub-Prime Automotive is a bubble but the size of it isn't so bad. The biggest problem is repercussions of such a bubble collapsing and becoming contagious.
Real Estate seems ok, nowhere near what happened in 2007 in terms of scale and corruption.
Student loans are a rather large bubble. Still nowhere near the size of the sub-prime mortgage nightmare.
Tech bubble, shouldn't be a big problem if it implodes by itself in the United States
China: I can't even speculate. Everyone has been screaming wolf about China for years and nothing has collapsed yet. China is rated #1 by the Economist as a risk of collapse which would take down the global economy.
I am going with: China or EuroZone banking melt-down that spreads and pops all the United States bubbles.