Like I said, I wouldn't be surprised if he gets canned because of the expectations of the job and, as you point out, the recruiting class he has right now is problematic. He has shown the ability to recruit though -- his classes have been #10, #4, #4 and last year #20 with a bad season -- so a strong finish and word that he won't be fired could turn that class around. But it is the expectations that will likely get him, especially if they bring in an AD with past ties to USC. For example if they lure Villanova AD Mark Jackson back to Southern Cal then good chance Helton is gone. But if they bring in an outsider and Helton goes 3-1 rest of the way (or better, 4-0) he might get another year to show what he can do. Especially if the search drags on because the interim AD has said barring something extraordinary he wouldn't be making the decision but leave it to a new AD.
What I find funny is the expectations USC fans/boosters have may not be very realistic (I know, when have fans/boosters let that get in the way). The Pac 12 has only had 2 representatives in the CFB playoffs and none the past 2 years (and very possibly none this year). Another funny thing is they might actually be better off keeping Helton next year. If they bring in a new coach his first game will be against Alabama, and while they'll have ND at home USC's Pac-12 road schedule in 2020 is Arizona, Oregon, Stanford, Utah and UCLA. Be much easier for a new coach to start his regime with a nonconference schedule of UC-Davis, ND and BYU and a conference road slate of Ariz. St, Wash. St., Cal and Colorado.