Currently Online 
https://www.ign.com/articles/ps5-shortage-has-reportedly-led-sony-to-make-more-ps4s-than-initially-planned
After it was reported that Sony was making more PS4s than initially planned (the report is from January 2022), Sony denied they were ramping up production.
So, I suppose it's 50/50 right now that Sony already discontinued the PS4 between April 2022 and March 2023 (their most recent fiscal year).
If Sony hasn't discontinued the PS4 yet, I think it's all but guaranteed to happen in the first half of 2024 or before. Chip shortages of the past 3 years and the PS5 playing 99.9% or so of PS4 games make it illogical to give the platform 11+years of availability.
Lifetime Sales Predictions
Switch: 161 million (was 73 million, then 96 million, then 113 million, then 125 million, then 144 million, then 151 million, then 156 million)
PS5: 115 million (was 105 million) Xbox Series S/X: 48 million (was 60 million, then 67 million, then 57 million)
PS4: 120 mil (was 100 then 130 million, then 122 million) Xbox One: 51 mil (was 50 then 55 mil)
3DS: 75.5 mil (was 73, then 77 million)
"Let go your earthly tether, enter the void, empty and become wind." - Guru Laghima
