Romelu Lukaku departed Chelsea this week, signing permanently with Everton.
He followed countryman Kevin de Bruyne in quitting the club, while Atletico Courtois and Eden Hazard remain.
Which way Thorgan Hazard is yet to be determined, but his loan side Borussia Moenchengladbach are keen to keep him.
Manager Max Eberl told German magazine SportBILD: "This is the next step for him. He possesses super qualities.
"The contract of Thorgan at Chelsea runs until 2016. Mönchengladbach has an option to purchase it."
Hazard himself revealed that his curiosity prompted the move to Germany, after spending two seasons on loan with Zulte Waregem:
"Although I had other offers, but I decided on Gladbach, because I see the best prospects for my further development there. I wanted to discover especially the Bundesliga."
Jose Mourinho had urged him to go and find regular playing time at a league which advanced him from the Jupiler Pro League, and he has a real chance to make a name for himself and step out of his brother's shadow.
Thorgan went onto play down comparisons with Eden Hazard, his more established elder sibling.
"He is now a great player, which I am very proud. But I am also therefore away from England and went first to Belgium, because I do not want to be compared with him."
If comparisons with Eden continue to grate, it could be one reason to depart Chelsea, for he will still have the dream opportunity to play with him for Belgium at international level.
Moenchengladbach are thrilled with his quick adaptation, scoring in his first friendly game, but there is a whole season to play out first.
If he steps up and delivers as he did in Belgium, the Bundesliga side are likely to push hard for him permanently, as may their rivals - it will come down to the player, and what Jose Mourinho can or cannot promise him for next season.