Explaining it would be difficult. Makes my head hurt.
However, there will still be familiar euro qualifiers for 2020. 4 of the 24 places though, will come from the Nations Leagues. For that, we'll be in a 3/4 team group with teams close to us on UEFA ranking. Those rankings have not been updated since 2016 I think, but will be fixed before the 2018 WC play-offs. Dunno if there are pots, or if its 100% by ranking.
NL group games are Sept, Oct, Nov 2018 before normal qualifiers start Mar 2019.