The first name that comes to mind is Ross Blacklock. With the current lack of depth at defensive tackle, Blacklock is coming into the fold at the perfect time. He's a big force that is capable of causing havoc up front, and I would be surprised if we don't see him near the top of the depth chart by the start of next season.
Now while he may not start right away, there is not a doubt in my mind that Isiah Chambers, the 4-star defensive end, should get extensive playing time this next season. Just like Blacklock he is a force up front and will help greatly with one of the most important things in football: Depth on the defensive line. Chambers and Blacklock could be a duo that we begin to fall in love with, opposing QB's not so much, over the next 3 to 4 years.
The player that I can see being used similar to Turpin, as a do it all type of offensive weapon, or a Nixon slot-back type, is Sewo Olonilua. He has the potential to play running back, special teams, or even play some linebacker like he did back in high school. Gary is a big fan of making the most out of what he's given by turning some offensive players into very good defensive players, so the latter may not be too far-fetched.
Due to all of the injuries last season, especially on the defensive side of the ball, we could see some more help in the secondary from some of the new talent. While a lot of freshmen played last season in the secondary, such as Julius Lewis, we could see KeShawn Somerville, 3-star cornerback according to 247sports, and 3-star safety, Innis Gaines come in and compete for the starting job right away.
However, there are still plenty of opportunities for some of the new guys to have an impact on offense. Taj Williams, John Diare, or Isaiah Graham, could step right into the (giant) shoes of Doctson and Listenbee and become TCU's number one wide receiver and deep threat. This part of the depth chart is what excites me the most. Our wide receiver core already has Emmanuel Porter, Jaelan Austin, Jarrison Stewart, KaVontae Turpin, and Ty Slanina. Now we are getting even more exciting play makers at the position. We might be spoiled with this class.