F1 supremo Ecclestone previously said that Rosberg winning the championship instead of team mate Hamilton would not be good for F1, but his latest statements appear to backtrack on that.
"Okay, not as popular as Lewis, but Nico was a very popular driver," he told PTI news agency. "So his absence is certainly not good for Formula One."
Ecclestone is also worried that Rosberg's potential replacement Pascal Wehrlein would not be a match for Hamilton.
That is the claim of Brazilian correspondent Livio Oricchio, writing in Globo Esporte.
However, Ecclestone isn't willing to influence Mercedes' decision.
"A lot of people are linking Alonso with Mercedes but I would like to wait and see what decision the team takes."
Big names seemingly ruled out
The German marque reportedly offered a discount of more than half on the British team's customer engine deal, as well as the services of junior driver Wehrlein, but Williams were unwilling to cooperate.
One reason given is that Williams' title sponsor Martini are keen to have an older driver with the team.
"For marketing reasons, the liquor giant needs an older driver,"claims Bild.
"Stop! It's not an issue. I have a contract with Ferrari in 2017," he told Blick
Bahrain International Circuit - Winter testing