This Is For You ScottN!
The future in "All Good Things..." was made by Q, and the whole thing never happened anyway!!!

The future in "The Visitor" couldn't have happened because Jadzia died 50 years prior to it. The future where Earth was assimilated in First COntact obviously didn't happen because the crew of the Enterprise stopped it.

The Future of Yesterdays Enterprise where Tasha becomes the mother of Sela (SP?) Never happened either because the Enterprise-C re-entered the rift and restored the past....but it did happen..what happened again. LOL

Aloha,

ROBMAN

In the TNG episode Firstborn a future Alexander comes back to kill his younger self. Well the future timeline that causes this never happens because the knife that the future Alexander carried had the mark of one of the Duras sisters' son. However, both Duras sisters were killed in Generations, seemingly before the one gives birth.

The future of "Timeless". Didn't Geordi still have implants?

The whole Star Trek universe won't actually occur. :-)

(Sorry. Couldn't resist.)

Obvious one - the Eugenics Wars didn't occur this year... Or in 1996 (Future's End)!

What, you don't remember them? They were staged during the TNG marathon of best episodes. Of course, they only lasted 5 hours, but they were the bloodiest wars in Earth's history. Everyone in the USA was too busy watching Star Trek to notice.

The future of Gene Roddenberry's where Humanity overcomes its baser instincts and works on self-improvement. Killed after Roddenberry died.

How do we know the Duras Sister was still pregnant when she died? She may have already had her baby!

We don't know that the Duras Sister was still pregnant when she died (hence my use of the word seemingly), however they never mentioned anything in generations, so I presumed that she still was. Now according to the TNG Guide, Generations occured between 48632.4 and 48650.1; Firstborn occcurred 47779.4. Now taking the latter of the Generations dates as the death date of the Duras sisters, the difference is 48650.1-47779.4=870.7

Using the conversion 1000 units equals one year we get 0.8707 year(s) or aproximately 10.5 months.

Does anyone know the gestation period of a Klingon?

Well lets say that she had the child, so it would only be a month old (or probably less), so it would be unlikely that a knife would be made with the symbol of the son on it. However even if it was made up, Alexander still has to get older, and by the time he gets as old as he should be the probability is that another knife would be made up that had different symbols on it (unless he is really attached to the knife, but in that case why did he lose it to Alexander!?).

Thus that future (in Firstborn) never happens.

I doubt that Alexander will now become a peaceful ambassador.

From what we know, the Klingon gestation period (at least in Alexanders case) is very short. We know that Worf and K'Ehleyr mated during 'The Emissary' (SD 42901.3), and Alexander was born on SD 43205. Given these figures, Alexander took just over 300 Stardate units to be born.
However this can be argued by that K'Ehleyr is not fully Klingon, so this could have had a effect on the gestation period.

Given how fast children grow in Star Trek spinoffs, if DS9 lasted one more year, Lursa's son would be exacting revenge on the Enterprise-E (formerly Enterprise-D) and assassinating Martok for Chancellorship. :)