Joe Dunne says he is expecting League One to be just as tough again next season.
Colchester United are preparing for a seventh successive campaign in the division, which is now beginning to take shape for next year.
The League One play-off final between Leyton Orient and Rotherham United takes place at Wembley, on Sunday.
And one further team will also be promoted to the division from League Two, with Burton Albion taking on Fleetwood on Bank Holiday Monday.
Doncaster Rovers, Barnsley and Yeovil Town were relegated from the Championship, while Scunthorpe United, Chesterfield and Rochdale went up from League Two.
And with the likes of Preston North End, Sheffield United, Bristol City and Peterbrough United remaining in League One, it promises to be a competitive once again next season.
U’s boss Dunne said: “It’s a tough division and it’s going to be just as tough, next year.
“I don’t agree that the league next year will be slightly easier.
“I think the teams that are coming up and coming down will form yet again the basis of an extremely competitive league.
“Teams generally with a top budget will get out of this league.
“But to get out of this division is hard and we’re set for another tough season - I’m not going to pretend otherwise.”
For all of the latest Colchester United news, including more on Dominic Vose's new two-year deal with the U's, see Friday's Daily Gazette.