Given the number of bikes a small increase in the quoted power output is likely to shift I would be surprised if the numbers quoted by Triumph are not the largest they can get away with if required to prove them.
There are several reasons why Triumph might under-specify the claimed power. The first is the emissions scandal, which obviously discourages exaggerated specifications, and Triumph's approach may be to measure more conservatively for newly released models. Ducati took the more radical approach of revising down the claimed power figures across their entire range for that reason last year. The second is that Triumph probably don't want to cannibalise sales of the Speed Triple, or confuse buyers of the Speed Triple. The third might be that Triumph want the Street Triple to be cheaper to insure, and the claimed power figure will be a factor in the insurance rating.
In any case, the empirical evidence is that the Street Triple 765 RS produces similar power per cc as the Daytona 675, and is in a similar state of tune, albeit with a slightly shorter rev range. This graph provides an approximate comparison based on fairly reliable dyno graphs published:
https://i.imgur.com/3p96Slb.png
It certainly feels that way too, and I say that as someone who's owned the previous Street Triple R, as well as quite a few new and old superbikes (including the Ducati 1299, 2015 R1, & Fireblade SP). The RS has a proper, peaky, sportsbike tuned engine.
As mentioned earlier the only "Moto2" clone to survive the latest emission regulations appears to be the Yamaha YZF-R6 and this required a reduction in power of 5.2 BHP compared to the previous version and 10.5 BHP compared to the one before that despite the significant revision of the bike. The latest emissions regulations have reduced the degree to which a bike engine can be tuned by limiting the amount of unburnt fuel that can be ejected from the combustion chamber at high revs. To burn more efficiently at high revs without losing a lot at lower revs is likely to require things like variable valve timing. Unfortunately the collapsed market for "moto2" road bikes seems unlikely to provide the insentive for this development and so we may well have to live with mass produced production bikes with a lower bhp/litre compared to what we have seen in the recent past.
The R6 isn't a Moto2 clone. Moto2 didn't use 600cc 4-stroke (all Honda) engines until 2011, and the R6 dates back to 1998. The R6/GSX-R600/ZX6R/675 Daytona/CBR600 are all supersports bikes. Their popularity waned as road bikes long before emissions regulations became restrictive. If they were still as popular as they once were, then the manufacturers could find an engineering solution to the regulations without unduly sacrificing performance. We certainly see ever more powerful 1000cc bikes despite the regulations, and some manufacturers (BMW / Ducati) have achieved that better than others (Kawasaki / Honda). But almost all are now knocking on the door of 200bhp. Despite the R6 being re-developed, the engine work appears to have focused on compliance (with more restriction) rather than re-development. By comparison, Triumph appear to have properly re-developed the 675 engine to meet tighter regulations and actually achieve proportionally greater performance consistent with the capacity increase.
So, I'd say it depends how much the manufacturers are prepared to invest, and the evidence so far is that they will for 1000cc bikes but not for 600cc bikes. But if you want a new Daytona, the Street Triple 765RS is basically that, in naked form. We might well see a faired version return, but I wouldn't expect any substantial engine tuning differences.