Well, let me see... A LOT to choose from as to the many, possible applications of the term "complex" and "complexity."
Jarkko's own announcement stated, in part, " . . . but because the project is quite ambitious and complex . . . "
pironi followed up, isolating and focusing upon the single word "complex," and suggested Googling the word, and provided its definition "consisting of many different and connected parts" ~ and then very pointedly said, "So... ???", as though the significance of that definition was significant enough to stand alone.
And maybe it DOES stand alone! It was one of only two terms that Jarkko provided. Sooooo, perhaps, therein, per the definition of the word, lies a CLUE.
Taking it a step further, the Googled definition of "ambitious": "(of a plan or piece of work) intended to satisfy high aspirations and therefore difficult to achieve." Well, what do you know, the definition provided is precisely 10 words!
I soooo admire the ability of contributors here to take their fine tooth comb to the immense and varied body of Leonard's work, and actually come up with potential possibilities [redundancy intentional]!
The only thing that I know for sure, given the definitions of the words Jarkko provided is that:
The components will be "connected," and my guess is that the common, silver/gold thread is Leonard. I wonder if he offered any suggestions for possible, future projects, or if the ideas and decisions related to this one are the work of Robert Kory and his team.
Given that the assessment of this project is that it's "quite ambitious," the commitment of this team to the quality of this project is, by definition, clearly unrelenting, even if their commitment translates to delays. They care and want this project to be worthy of Leonard, and for us, who love him so, to be both grateful and happy to have it.
I am SO looking forward to it!!

"Be yourself. Everyone else is already taken."
~ Oscar Wilde