According to the current creative team of Mike Curtis and Joe Staton, the characters in Dick Tracy's universe are well aware of those in Bill Holbrook's On the Fastrack. In a sequence from January 15, 2015, Honeymoon Tracy was reading an e-book starring Dethany Dendrobia, an "On the Fastrack" character (see: Dick Tracy and the Literary Double).
January 15, 2016, the following appeared in Dick Tracy (top), and On the Fastrack (bottom).
Dick Tracy discusses the e-book case with Dethany in person, while in Fast Track, Dethany investigates in cyberspace -- and crosses paths with Dick Tracy. It's a great crossover, thoughtfully executed by both strips.
And I found a few noteworthy things to consider. First, does this mean that Dethany -- and by extension -- the entire Fast Track cast exist in the same world as Dick Tracy? That's a change from having them exist as literary creations in said universe.
Second, note how Holbrook reinforces the concept of identity theft in his strip. He first shows Dick Tracy, then in the final panel, Fearless Fosdick, Al Capp's satirical take on Tracy -- a character that in some ways did indeed steal Tracy's identity.
One more thing -- the first crossover of these two strips (to my knowledge) occurred 1/15/15, the second 1/15/16. Is this going to be a yearly thing? No complaints from me if it is!