This just in, from a well known (and usually very reliable) cicloweb user based in Piedmont:
1 Torino ITT
2 road stage somewhere near Torino
3 Torino? - Novara
4 Biella-Alba
19 ??? - Alpe di Mera MTF
20 Verbania-Madesimo (via San Bernardino and Splügen)
21 Milano (not known if ITT or road stage)
The final stages being in Piedmont are pretty believable considering the weird rest day after stage 16 - there is likely gonna be a transfer.
Alpe di Mera
San Bernardino
Splügenpass (from Splügen, 10 km of descending false flat away from the end of San Bernardino's descent)
The last combo is pretty good, but going to Switzerland is risky... just like France last year.