Considering that Guercilena said at Radiocorsa that he thinks the Giro is the best preparation for Olympics probably he won't even go in France. More likely scenario at the moment is something in February, Strade, Tirreno, Sanremo, training camp, Tirol, Liege, Giro, training camp for Olympics and after Olympics probably Vuelta and then evaluating if shape will still be there/there won't be too much fatigue for Worlds. Nibali himself a couple of weeks ago on the paper Gazzetta stressed the fact that for Worlds they'll see later in the season if it's doable but are Olympics the big target.I like his ambition but I fear the Giro GC is a bit of an overkill.
I also hope he only does two weeks in the Tour to arrive fresher to Tokyo.
IMHO is a wise decision to let the Worlds on doubt if Giro is a big target, with a second peak for Olympics you can carry the form for a good Vuelta considering that this year will be anticipated to mid August but then is an unknown for the fall, unless your name is Valverde.