The iPad can almost certainly handle massive images just fine. The industry has been getting by with that sort of processing power for some time. I can't comment on support for 10k images specifically, but 4k video editing works pretty well, and 30MP+ images too (so 8k-ish?). And while there's a segment of pro work that needs 10k+ support, it's not everything – just because the whole professional market isn't supported doesn't mean a segment of it isn't! (I haven't had much call to edit anything in excess of 4k for a long while, despite using Photoshop pretty heavily).
The input methods might be a challenge, like I said, but it's possible to think of ways in which a good editing experience might be achieved, with the compromise being worth the trade-off in portability – but we'll need to wait and see before jumping to conclusions!