The DRTES put peak demand in 2030 at 15k pphpd. That's easily met by ICTS scaled vehicles traveling at 90s headways.Also, reintroducing ICTS just as we got rid of it with the SRT closure also seems unwise - Steve Munro estimates the capacity of the line to be 4 subway-car length which would probably push an ICTS to 6 car length on day one with no fleet economies of scale to take advantage of either from the conventional light rail or heavy subway direction.
Reintroducing LIMs probably wouldn't be a good idea, but any new route should designed to realize all of the cost savings possible. Things like running through a single tunnel, or tighter turn radii and grade allowances.
Also, economy of scale in rolling stock seems nonexistant in Toronto.