No one knows. It's impossible to know. Anyone who tells you they know is lying.
Look, are you retired today? Are you retiring in the next 10 years? Or is retirement farther out?
If retirement is 10-20 or more years away, you just stay the course. The next 10 years might indeed have low returns. But then low returns are usually followed by years with good returns.
The long-term 10% nominal historical average annual return of the stock market INCLUDES all the crashes and the bad years.
We don't get 10% during the good years, and 2% during the bad years.
We get like 18% during the good years and 2% during the bad years, and it still averages out to 10% a year over the long-run.
Sure, it would be great if one could get out of the stock market during those 2% years, and invest in something else, but it's very difficult to time the market successfully. And if you miss a few of the good years if you get out early because you're expecting bad years, it can really cost you.
Just staying in over the long-run, so far, has made us rich. Will the future repeat? Nothing is for sure. But, so far, bad years are followed by good years are followed by bad years are followed by good years.
Now, if you're about to retire, you need a good chunk of your money in safer assets like CDs, or a bond fund. They don't pay much interest today, but they are still safer than stocks. You still need some money in stocks for the long-term gains, but you need some money in the safe assets now to buy food if stocks crash next year.
I'm close to retirement and I'm 50/50 stocks/bonds... I'm not worried about the stock side doing poorly for the next 5-10 years because even if it does, I have plenty of money on the bond side to get me through the bad years.