There is a notice on the German Druckerchannel forum that Canon is phasing out a range of Megatank printers - the GM2050, GM 4050, G 5050, G6050 and G7050. Direct successor models are not known.
https://www.druckerchannel.de/artikel.php?ID=4868&t=abkuendigung_canon_pixma_megatank
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