Interim boss Guus Hiddink has admitted Chelsea face a period of uncertainty in the likely absence of Champions League football next season after the defeat to Paris St Germain.
The Blues on Wednesday were dumped out of Europe as PSG won 2-1 at Stamford Bridge for a 4-2 aggregate success in the last-16 tie.
Chelsea are well adrift of qualifying through the Premier League - the Blues are 10th, 10 points behind fourth-placed Manchester City, with nine games remaining - 10 months after winning the title.
And next season appears likely to be Chelsea's first without Champions League football under the ownership of Roman Abramovich, who took over in 2003. Their most recent season without top-level European competition was in 2002-03, when they played in the UEFA Cup.
"Chelsea is now in a transition period," said Hiddink, who has restored stability following a turbulent start to the season under Jose Mourinho.
"They have to see how to go on and try to regain the lost terrain where Chelsea used to be. Chelsea must consider its short(-term) future, how to handle this."
Chelsea's only losses under Hiddink have been inflicted by PSG, who advanced to the quarter-finals for a fourth straight season and a second in a row at the expense of the Blues. The Dutchman insists his deal is only until the end of the season, when Chelsea will seek to appoint a permanent successor to Mourinho.
Chelsea's woes have been personified by Eden Hazard, who was again disappointing.
The Belgian playmaker, Chelsea's leading performer in last season's Capital One Cup and Premier League double, was booed by a handful of home supporters as he was replaced 13 minutes from time, nursing a hip injury which makes him a doubt for Saturday's FA Cup quarter-final at Everton.
Hiddink said: "Yes, they had the right to do what they think. You can express always your feelings."
Hazard had at half-time swapped shirts with Angel di Maria, something Hiddink said he did not approve of, although he refused to condemn the Belgian.
"I'm aware. It should not be done," the Dutchman said.
"But in some countries it's usual that you do it (at half-time) and not after the game. Maybe they're both used to doing that.
"Don't overvalue this issue."
Diego Costa did perform well for an hour, netting his second Champions League goal for Chelsea and 11th in 15 games under Hiddink, before he was substituted with an injury which, like Hazard's, requires assessment.
Hiddink added: "Diego was desperate to play, although not 100 per cent fit. I don't know if that became worse. I don't know if it's worse than before the Stoke game (which Costa missed as a precaution)."
Away goals had separated the sides in the last two seasons - Chelsea won the quarter-final tie in 2014, but were defeated at the last-16 stage in 2015 - and John Obi Mikel's strike on February 16 at Parc des Princes gave Chelsea a fighting chance.
Costa cancelled out Adrien Rabiot's opener before Chelsea conceded soon after he left the action as Zlatan Ibrahimovic struck. It was a cathartic moment for the Sweden striker, who missed the 2014 tie through injury and called Chelsea's players "babies" following his sending off 12 months ago.
PSG boss Laurent Blanc lauded Ibrahimovic for his performance.
He said: "Zlatan performed at the level that he has been performing throughout this season. I don't necessarily think it's going to give him any more confidence. He has plenty of that as it is. He scored the decisive goal and laid on an assist."