I don't see Jacksons as much of an issue because they are themselves so fragile, however the IS2 would represent a major threat. Even so, it is as always a matter of balancing, it's entirely possible that despite those two being serious threats it's still a viable faction competitively, even in team games. At worst it could be a faction that is balanced in 1v1 and to some extent 2v2, but outclassed by the opposition in 3v3 and 4v4 (again, pretty much like USF and arguably allies as a whole!). I'm not convinced they wouldn't have units capable of dealing with them though. Even without OH / OKW allies.
Ita has medium tanks with 47mm and long barrelled 75mm guns available for the time period. Few that ever saw combat prior to the Armastice, but some that kept on fighting under German command later on. It has a 75mm AT gun it could theoretically use. It even has a
90mm tank destroyer that was produced in highly limited quantities. And a
105 as well. A static
90mm AT gun / AA gun that was actually used existed also.
Combined with various kinds of infantry, mortars, mgs etc, there is certainly the potential to actually have a faction that would be interesting to use and competitive. Let's not pretend like they've ever let the complete obscurity or lack of historical use ever stop them from including units in the game before anyway, so there's definitely room to use some of those "tanks that got delivered 2 months before the armistice then got used by Germans in Italy from then on". And units that were poor in RL but awesome in CoH, or vice versa.
Naturally the best we could hope for from Relic is "Africa Korps, featuring one commander who uses some Italian ostruppen style useless idiot infantry!"