Can now() roll over just like millis()?
now() is a function that is specific to Intel Curie based boards. 

It returns an unsigned long (which on a 32-bit system is the same as an unsigned int) and so can provide the number of seconds since 1/1/1970 up until the year 2106, at which point it will roll over.

If you plan on having your system run continuously for more than the next 88 years you will have to deal with that rollover correctly, including:


Using subtraction to "wrap around" your calculations
Not trying to calculate any periods longer than 136 years