Dirk Valentine 2?

Did anyone notice the Dirk Valentine-reference in the 15th level of Final Ninja Zero?
If you find the message in level 15 Monty, the old guy from Dirk Valentine appears and says

Okay Dirk
Hang on, you're not Dirk!
Must be a side effect of this blasted Martian radiaton.

When you finish Dirk Valentine the ending screen says

...And Dirk, he returned to England only to encounter a little problem in...
Dirk Valentine and the Martian Underworld....

Dirk Valentine 2 coming soon?