Note 4 at Jn. 9:4: Jesus is the light of the world (v. 5) so Jesus is obviously not speaking of a time when He would be gone from the earth in His physical body resulting in no man being able to do these miraculous healings. Since His disciples in the first century (and also today) did the same miracles of healing that Jesus did, this must be more specifically speaking of the three-day period between the crucifixion and the resurrection. Jesus is saying that He wouldn't always be here on earth in His physical body, so He needed to take advantage of this earthly opportunity to minister.

This statement could also parallel John 11:7-10 where Jesus was speaking of walking in the light if we were following God's leading and walking in the night if we weren't. This would then mean that Jesus must fulfill God's will (walk in the light) and heal this man because His ministry on earth was about over. Jesus realized there was a limit on His earthly ministry. Likewise, we don't have forever to accomplish what God has given us to do. Our "night" is coming.