A relegation system isn't the best idea as many teams from high levels will relegate and promotion at some point would be almost impossible.
Tanking if you want to call it like that, isn't actually a bad thing, if you play the game for many years you might actually end up at that point when you will see it as an escape to take a break for a short period of time. Top Eleven isn't a game where you can pause it or something, the game goes on even if you want or not so you might need some breaks from time to time.
Tanking wasn't a huge issue actually, only now cause they started to exploit the Associations using the tanking system but otherwise it didn't really harm the game to much.
Personally tanking should stay cause I know many good managers who would quite if it wouldn't be for this. The only problem is how you use the tanking and if you decide to exploit cause if not, you don't harm anyone.
Is not a term I am using "tanking" as I do not keep my team over the seasons to get it stronger, pretty much I wipe out all of them if I really do this and yes I did it several times and more likely at some points I might do it again. Sometimes I woke few weeks straight up to 60 hours a week and I literally do not have time to play properly so for me is like a short break, a short escape that allows me to continue my career from almost the same point.