It's kind to the vast majority of teams that get relegated out of the championship.
Of the 49 different clubs (MK Dons and Wimbledon treated separately) to be relegated to the 3rd tier at some point since 2001 only 13 clubs haven't returned at all. Some have come back up and then subsequently been relegated again, others have stayed up and not gone back down. It tends to level out with clubs of our size ending up back in the 2nd tier, and the vast majority of those who have suffered relegation and never come back are small clubs so it's no surprise in their case.
Basically every single club around our size comes back and most pretty quickly. Reading are currently the only club around our size who have gone down in that time and are yet to return, granted it's only 2 seasons so far for them and they are already very competitive despite being an absolute circus.