Lukaku doesn't look to me like a striker that Bayern would fancy that much, i am not saying it is a completely impossible move, but it is close to that, Lukaku is more about his strength than his clinicality and precision, and Bayern is more of a technical team, and i think Lukaku would be unsuitable for them.
Having said that, a return to the Italian Seria A looks like the best option, but Chelsea would be sweating currently, they spent quite a lot of money on this player less than a year or so ago, and now he wants to leave, and that is not just the problem, if the blues are to sell him, they are going to run at a huge loss, cause i do not think any club would take Lukaku close to the amount Chelsea spent on him, not to even talk of footing his wages. I think the way out for Lukaku at this point in time would be via loan, but whichever it is, Chelsea are the real losers in all of these.
No one can be insured against losing trades, sometimes this happens. Lukaku is still young and a very promising striker, but it takes a lot of work to be the best. To the level of Bayern, he still needs to work a lot and grow. Lukaku has made no secret of his desire to return to Serie A, while Chelsea want £20m for the Belgian's one-year loan. There are also rumors that Conte wants to intercept Lukaku at Inter, and invite him to Tottenham. But as I understand it, we are not talking about buying, in all cases it is a lease with a subsequent possibility of redemption.