What happens in the duo of Tails and Knuckles if only Knuckles will survive? Sonic.exe SoH

What happens in the duo of Tails and Knuckles if only Knuckles will survive? Sonic.exe SoH

https://www.youtube.com/watch?v=i4GgC4ALlM8

http://www.nicovideo.jp/watch/sm33615631