The i7 ad i9 being RPL+ isn't a bad sign for Intel 4 imo. Because RWC doesn't increase IPC/clocks high itself by itself to compete with an extremely mature Intel 7/10mm process hitting 6GHz. With how old (and refined) 10nm and 14nm became, newer nodes are going to face an issue reaching equivalent fmax clocks. However that prob isn't going to be an issue for ARL, considering LNC is supposed to bring a hefty IPC increase, meaning it could bear slightly lower fmax and still get higher perf, and also because Intel 4 won't be nearly as mature as the 10 and 14nm desktop products.
But more importantly about the lack of i7 and i9s, Intel 4 should be capacity limited, it being their first EUV node, and them not having nearly as many EUV tools yet. It would make sense to focus on the premium market first, that being high premium thin and lights. And they will have i7 and i9 mobile parts there, just not for desktop. And considering that mobile is a much more profitable and important segment for Intel, it makes sense to focus there.
Edit: Oh and I forgot to add, ARL desktop is supposed to be on TSMC. So the node problem shouldn't be an issue there.