I don't think this will happen. Sidekicks are usually T-Mobile exclusive phones, meaning T-Mobile is the only carrier selling these phones to customers.
Also, only the Sidekick LX 2009 would work on the Wind network, since Wind uses 1700Mhz.
t-mobile uses the same network us us and most their phone do work with us, look at the HTC nexus. it only has the 2100 nothing about the 1700 and works with us. Frequencies / Bands: HSPA: AWS (1700,2100), 2100 MHz.
t-mobile uses the HSPA: AWS network too
works on their network cause nobody uses it till now, wind dose.
Wind uses 1700Mhz as well. See here:
http://en.wikipedia.org/wiki/UMTS_frequency_bands