The OP seems to be claiming that GTA IV has seriously hurt the sales of Mario Kart Wii. I would say that Mario Kart Wii is performing just fine compared to other recent Nintendo releases.
http://vgchartz.com/swlaunch.php?reg1=All&game1=Super+Mario+Galaxy+-+Wii®2=All&game2=Super+Smash+Bros+Brawl+-+Wii®3=All&game3=Mario+Kart+Wii+-+Wii&weeks=30
I would say there's no way the Mario Kart Wii launch could have gone any better.
As for Nintendo going head to head with GTA IV, I think the amount of hardware that Nintendo moved last week speaks for itself.
Switch Code: SW-7377-9189-3397 -- Nintendo Network ID: theRepublic -- Steam ID: theRepublic
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Switch - Super Mario Maker 2 (2019)
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