This would definitely discourage tanking hahaha.
Being a European football fan myself I can obviously appreciate this. In fact, if I was starting a league and I knew for sure it would be have a sustainable 90ish members all the time (like the VHL), I would implement a 6 team top league and 6 team lower league. If, like IRL, relegation meant mass departures of the best players, and promotion means panic buying whatever loose pieces available, it could potentially be fun. Have a ridiculously low salary cap, avoid powerhouses and magic!
"In many European soccer leagues, this means that, hypothetically, a small local team could one day be in the Premier League."
Not even hypothetically! Granted, not the Premier League but in Spain's top division this season is this tiny team: http://en.wikipedia.org/wiki/SD_Eibar
In fact, they're currently an impressive 8th in the league!