The Future Is Unknown was created on 2004-03-28.
It is correct to use "which is" when talking about a singular future unknown situation or option. If referring to multiple future unknown situations or options, it is correct to use "which are."
Yes
It is unknown what the future holds considering technology.
Sender Unknown was created in 2006.
That is unknown. What it happen in the future is not known.
Unknown Africa was created in 2007.
Lurking Unknown was created in 1967.
Neon the Unknown was created in 1940.
Unknown Delight was created in 1982.
Giant from the Unknown was created in 1958.
A Feast Unknown was created in 1969.
Journey to the Unknown was created in 1968.