> I see no fundamental limitations that would prevent further improvements
How can you say this when progress has so clearly stagnated already? The past year has been nothing but marginal improvements at best, culminating in GPT-5 which can barely be considered an upgrade over 4o in terms of pure intelligence despite the significant connotation attached to the number.
Marginal improvements? Were you living under a rock for the past year?
Even o1 was a major, groundbreaking upgrade over 4o. RLVR with CoT reasoning opened up an entire new dimension of performance scaling. And o1 is, in turn, already obsoleted - first by o3, and then by GPT-5.