Would you expect it to be any different at Purdue who will have 7'3" Senior Matt Haarms and 6'9" junior Trevian Williams ahead of him? I think we land Miller, Kalkbrenner, Curbello or Watson & Kasabuke, or the wing from Curie who's name escapes me at this time.
Not sure why you're making the comparison with Purdue. But sure let's make the comparison.
I expect Purdue's 2020 starting lineup to look something like
1/2: don't matter for Kalkbrenner's playing time
3. JR Aaron Wheeler (6-9)
4. JR Trevion Williams (6-9)
5. SR Matt Haarms (7-3)
with contribution at the 5 from SO Emmanuel Dowuona (6-11)
If Kalkbrenner goes to Purdue he can compete with Dowuona and play ~10 backup minutes to Haarms in 2020. Then in 2021 the starting role is all Ryan's.
I expect Illinois' 2020 starting lineup to look something like
1/2: don't matter for Kalkbrenner's playing time
3. JR Tevian Jones (6-7)
4. JR Giorgi Bezhanishvili (6-9)
5. SO Kofi Cockburn (7-0)
with contribution at the 5 from SO Bernard Kouma (6-10) and contribution at the 4 from SO Benjamin Verdonk (6-8)
If Kalkbrenner comes to Illinois he can compete with Kouma and play ~10 backup minutes to Kofi in 2020. But Kofi's likely not going to the NBA after just 2 years so he'll still be around in 2021 (I'd love to be proven wrong on this!). So Ryan's going to be looking at backing up Kofi again in 2021 with Giorgi still playing as well.
Maybe he'd be able to backup both Giorgi AND Kofi in 2021 and work his way up to 16 minutes per game. But he's not looking at cracking 20 minutes until his 3rd year with Illinois (again unless Kofi leaves after just 2 years).
There are a lot of teams out there like Purdue that will have openings for Ryan in year 2 and he's going to end up at one of those programs (unless Illinois can really sell him that Kofi's a 1AD player).