I have no crystal ball, but for the S&P493 to grow they would likely need better earnings, and earnings expectations continue to decline. Chart below is from Apolo. A bit dated but its gotten worse not better.I think that's a bullish signal for the overall economy. There is tons of room for growth and gains to broaden out.
https://www.ishares.com/us/products/239693/ishares-msci-usa-etf
Mid and small caps are even worse. If the economy was growing usually they benefit also - but haven't.
Some keep talking about the "broadening out" that is supposed to happen but never does. I had some holdings in the RSP equal weighted ETF, but in the new year I sold it and moved that money to off-shore. Off shore had done pretty well comparatively - like 10% YTD, but not even close to my mega cap stuff.