Promotion/Relegation for leagues

I was wondering if this system should be implemented to give bottom tier teams a chance to not get relegated and to make sure that the teams that get promoted are considered as good as the league itself.

Maybe like the top tier teams from division 4 , 1st and 2nd play against 9th and 10th from division 3, in best of 5 or group stage format sort of thing. What you guys think?
This is an interesting idea, because this is how it works in LCS, LCK etc, however, because I don't think this is necessary in the lower leagues, it would likely create some sort of gap between seasons.
Henri has talked about something similar but unfortunately we just don't have the resources at this point to make this happen. But definitely in the future.
I like this! Maybe change it to where if you win your Division you get auto promoted and if you're last you get auto relegated though. Would serve as a reward/punishment for the season then play the bo5 between the 9th team from D1(for example) and the 2nd team from D2.
this would be awesome and those that prove to be good enough would get their deserved promotion , most teams that get promoted to div1 are demoted straight away