Fill mains in ranked?

I like all roles, so I fill in all ranked games. Will the new ranked system make it so I'm only really placed in support, adc, and jungle roles then? I'd say I draw top 1/20 games and mid 1/50, and even then often times trade out of them because someone got autofilled support and I'll take an appreciative teammate over a grumpy one any day.

I selfishly wish there were incentives to choose "fill" as an option. The new system seems like it discourages it.