Forget about thinking about how best to structure your portfolio of ETFs. The truth is, buying ETFs does not mean that you are investing passively. If you have heard of the sector rotation theory, you would probably know that people are investing into sector ETFs at different times of the year.
What passive investing is meant to be
In the true spirit of passive investing, you should be continually investing into the same portfolio, and not selling it. In the same token, your portfolio should be also be truly diversified over every sector, every country, and every market, market capitalisation weighted.
In that sense, you should just buy the ETF that just buys every stock in the world, market capitalisation weighted. For myself, I put into the Vanguard All-World UCITS ETF (VWRL), but this is not a fund recommendation for you.
Note: the ticker has been changed from VWRD …