Even if he was going back to the chelsea and it will not be included in the starting line up and so there's no choice for him other than try to stay at intermilan. Intermilan's owned was also trying to sell its club. That means the future for this club is still remain unknown.
Lukaku has been taking a good decision by staying at inter rather than going back to the chelsea again but i don't even think inter will make him permanent caused by club was facing financial problem.
The owner of inter will be facing the dead line to pay the loan. that's also a very big loan.
Returning to Chelsea not guarantee for Lukaku get regular position under scheme Graham Potter depending his performance in this season with Inter Milan not quite, absent several games with Inter Milan trough still injury I think need for Lukaku scoring goals again if want get regular position at Chelsea. However new manager at Chelsea seems the same if Lukaku can't back to top performance again and seems Graham Potter not easy to give regular place for Lukaku. Still left one half season more and I think if Lukaku can back to quite performance Inter will try several option to extended loan or permanent with Lukaku transfer from Chelsea.
It seems to me that the most suitable option for Lukaku would be to somehow remain at Inter. He went to Chelsea for the 2nd time and he failed to deliver for them and returned to Inter which was not taken very light-heartedly by Chelsea fans. Aside from that, I also believe that his ability to score goals has declined quite a bit in the past couple of years as a result of his age. While he was in Everton he used to score bags of goals here and there and now he just can't. Further, I do not believe that Potter is going to be able to play him regularly if he continues to play in this poor form.