Final F9/H core serial

[eeergo]

Related to this 2017-18 thread I believe there has yet been no such a poll. Both in that topic's last few posts as well as in most SpaceX threads there is a general sense of consensus that the end of F9 flights is not beyond sight.

This can be because you believe SuperHeavy will take over or because of other assumptions, but I wouldn't delve too deep into that here in order to avoid excessively speculative discussions.
The question as to how many *flights* will take place between now and the retirement of the Falcon system is related, but of course highly dependent on the final reusability factor they can squeeze out of current and future cores.

We kind of have an estimate, based on then-current factors, from 2 years ago: 300 flights (minus about 20 performed since then, so around 280). That number may or may not have changed based on the -many- intervening developments, and likely will in the future, but could constitute a "foreseeable future" horizon. Based on that, and considering current reusability rates as an optimistic minimum (i.e. 4-10 flights per booster), you'd need between 70 and 30 cores (i.e. B1090 to B1130, approximately).

Likewise, another interesting point to think about is how many cores the Falcon fleet will consist of *at any given time* - for example, this Wikipedia list shows 8-9 cores which should be ready to perform (re)flights. As far as I'm aware, the latest new-build core we have news about is B1060, so there should be a 9-10 core fleet at this time. Will it, on average, shrink, grow or stay roughly stable?

The last poll option covers the possibility of further post-Block 5 evolutions (I know SpaceX has stated they wouldn't go into a "Block 6", much less a radically new design, but this option covers the eventuality that due to whichever rationale this does become feasible). It is questionable, and largely subjective, whether there's even space for such a redesign - large enough to warrant a first-digit change (B1XXX->B2XXX) but which still doesn't change the F9 core so much as to make it become a completely different rocket, especially considering the large v1.0 -> v1.1 in-depth redesign didn't cause such a designation change (but those were different times, and marketing may have discouraged such a rebranding of a then-yet-to-certify, young system).

[eeergo]

Even though nobody of the 20 voters so far has explained their rationale, it is so far remarkable that there is a pretty solid statistical distribution peaking at the 4th option (B1100-B1200), and falling precipitously beyond that - so indeed most people believe we ought to see the use of at least as many new cores as have been fabricated so far, over all Falcon variants.

Considering an average of 30 launches per year, and 6 average (re)uses per core (wild guesses, I'm not sure if conservative or optimistic actually, so I'll call it reasonably even-handed), this would mean the most popular estimate for retirement of the Falcon system to be around 15 years from now (2035), give or take 7 years. Interesting.

[Zed_Noir]

If there is continual high attrition rate with the Falcon Heavy center cores along with possible expendable Falcon Heavy center cores for high energy missions. Then there will be some cores with short service life of a few or even single flight.

[meberbs]

Even though nobody of the 20 voters so far has explained their rationale, it is so far remarkable that there is a pretty solid statistical distribution peaking at the 4th option (B1100-B1200), and falling precipitously beyond that - so indeed most people believe we ought to see the use of at least as many new cores as have been fabricated so far, over all Falcon variants.

Considering an average of 30 launches per year, and 6 average (re)uses per core (wild guesses, I'm not sure if conservative or optimistic actually, so I'll call it reasonably even-handed), this would mean the most popular estimate for retirement of the Falcon system to be around 15 years from now (2035), give or take 7 years. Interesting.

More votes now, the B1100-1200 has 100 core numbers compared to 20 each in the 2 previous options, which at the moment have a combined 60% of the vote, with peak on the 80-100 option. I would guess that most of the 1100-1200 are expecting the lower end of that. This would significantly pull in the expected end date based on your calculation (which seems good enough for a WAG)

I went with 1160-1180 since that fits Musk's prediction of around 30 Block 5 cores (which equals B1075 as the last) I think it may tip over into the 1180 range though depending on if the military (or NASA) has some launches insisting on new boosters towards the Falcon end of life, which won't end up reused at all as all other customers will have moved on by then.  I predict EOL around 2025, as commercial crew (expect all new boosters) and NSSL phase 2 wrap up.

[Comga]

People should stop summarizing the interim results in their posts.
That's for the poll originator to reveal, or after the voting.
It is OK to say what you chose and why.

I chose the fourth options B1100-B1200 because I think there should be many years left for this successful but not-far-from-traditional rocket, and that there will be leakage, landing failures, expendable missions, that require replenishment.
But I see the merits in guessing B1080-B1100. 
By 80 cores they may have the leakage rate down to <10%, so that cadre alone might be 200 flights, several years wroth, and time enough to prove out Starship. 
As always, time will tell.