Aguero has fallen down the pecking order since the arrival of Gabriel Jesus last month and has dropped to the bench for the last two games.
The Argentine admitted after their 2-1 win over Swansea he intends to remain at City but will assess his options at the end of the season.
And, according to The Sun, City boss Pep Guardiola will turn his attention to Dortmund hitman Aubameyang if he loses Aguero in the summer.
Pierre-Emerick Aubameyang eyed as Sergio Aguero replacement
The Gabon international has emerged as one of Europe's most targeted strikers after joining Dortmund in 2013, scoring 101 goals in 167 appearances since.
City are reportedly willing to spend £40million-plus to bring the 27-year-old striker to the Etihad Stadium, but are likely to face competition from Real Madrid.
The former AC Milan youngster has made no secret of his desire to one day join the La Liga giants and could look to replace wantaway Alvaro Morata in the summer.
Sergio Aguero's Manchester City future up in the air
Premier League Done Deals: Every transfer in during January 2017
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Aubameyang, who has 21-goals this term, recently admitted he needs to leave Dortmund in the summer to reach the 'next level', with Real still stop of his list.
He told French outlet RMC Sport: "If I want to go to the next level, I need to leave in summer.
"Real Madrid is still a dream, but there has been too much noise."