Will Jesus' second coming be visible to all?
Yes. No.
Matthew 24:30
And then shall appear the sign of the Son of man in heaven: and then shall all the tribes of the earth mourn, and they shall see the Son of man coming in the clouds of heaven with power and great glory.

Mk.13:26
And then shall they see the Son of man coming in the clouds with great power and glory.

Luke 21:27
And then shall they see the Son of man coming in a cloud with power and great glory.

Revelation 1:7
Behold, he cometh with clouds; and every eye shall see him.
John 14:19
Yet a little while, and the world seeth me no more.

Thanks to the WatchTower Society for pointing out this contradiction. (Reasoning From the Scriptures, p. 313, 342-3)