Hey Jarred, will all these low-end GPUs be obsolete with the arrival of the new APUs imminent?
That all depends on what AMD does with its desktop parts. We know the Rembrandt Ryzen 6000 series mobile APUs have up to 12 CUs and are paired with LPDDR5-6400 memory, but there's no desktop equivalent yet, and may never be.
Some are hoping Ryzen 7000 series APUs will have up to 16 CUs, others think maybe 12 CUs, and I've even seen hints that they could be as little as 4 CUs — basically just a minimum level of graphics functionality, similar to Intel's UHD Graphics 770 that only has 32 EUs where the laptops can go up to 96 EUs.
A 12 CU Ryzen 7000 APU clocking the graphics at over 2GHz and paired with DDR5 memory would at least be competitive with the RX 6400 — less bandwidth (and it's shared), but a closer link to the CPU might make that a moot point. Probably call it a slight advantage for the RX 6400 in gaming performance, but the Ryzen APUs will have all the missing media encoding functionality that Navi 24 lacks. If it's only 4 or 8 CUs, though, it's not going to be very useful for anything more than 720p gaming.