Is it worth to refrain from investing in expectation of a financial downturn?

The point of dollar cost averaging is to invest no matter how well/bad the market is doing! in fact, in a bearish market, your average cost per share would be reduced, which is good! this way, when the market eventually turns bullish again, you'll stand to gain if you decide to sell your holdings.

When market becomes bearish, it is the best time to look for undervalued stocks (stocks on discount). As long as fundamentals do not change, you shouldn't sell any stocks off. ETF works by DCA, so during a downturn, average unit price will decrease and you'll profit more when the market picks up.