I think it's more a matter of getting full yield from the die. That means having all 84 of the SMs working instead of just 82.
The main problem with "Titan" is power consumption, not the % of die enabled. That's why marketing throws at us "Titan-level performance" this generation and not a proper titan card.I would be extremely surprised if they made a Titan on this generation, or that would be hard trolling imo. On a die of this size, the yield would be noticeably reduced just to enable 100% of the chip instead of 98%, thus a big bump in price (from an already high price), just to get 2% extra performance. They introduced the 3090 as the Titan of Ampere, unless there is a refresh (that would be in at least a year), there won't be a more powerful Ampere GPU than the 3090.