New Who's strong in mobile GPUs now?
Apple, Qualcomm / Adreno on all Snapdragons and ARM / Mali on everything else (Samsung, HiSilicon, Mediatek).
IMG / PowerVR has been pretty much gone from the news for the past couple of years. Outside of a couple of TV SoCs where 3D performance is rather irrelevant, the only design win they got that I can remember from the last couple of years was Mediatek P90, and I don't see a lot of Mediatek P90 phones out there. Mediatek was fairly successful this year with the G90, which is a "gaming-oriented" mid-range SoC and has a Mali GPU...
So yeah, without the Apple licensing deals IMG is done for. With the AMD RDNA deal, Samsung probably isn't coming back to IMG anymore and the chinese companies seem to prefer ARM GPUs even for their gaming and high-end solutions.
And why wouldn't IMG or their new owners sue the pants off Apple, they could effectively block Apples iPhone and iPad sales and would be wading in damages!
Timing.
Apple announced their "separation" from IMG in April 2017, and their wording implied a "gradual decline" of IP licensing from IMG, not a sudden drop for their Ax SoCs. Meaning that gradual decline would probably mean they'd get to stop paying IMG a couple of years down the line.
IMG instantly got in financial trouble after that announcement (duh), meaning there was a chance they'd file for bankrupcy between then and now. Had that happened, apple wouldn't have to pay them a cent (your company can't sue anyone if your company doesn't exist).
But in late 2017 IMG got acquired by a chinese investor who got the cash flowing again, so after that same couple of years apple had to renew the licensing agreement.
Typical corporation power moves IMO.