First, there had to have been more than 144,000 Christians during the first century alone......
Beyond this, how could it be that only 144,000 were faithful between 98 AD and 1872?
Good points! While the first one you mentioned could be debatable the 2nd one brings up some interesting arguments. If the number wasn't filled in a total of 1800 years with all the Christians that died trying to be faithful then Jehovah must be a very had to please dude because about a hundred thousand spaces were left open for the modern day JWs to fill or close to it if we look at the memorial partaker that reached a peak leading up to the cutoff date 1935(I don't know the exact figures but it was up there.)
There present position needs some serious tweaking to even satisfy the most brain dead JW if they know anything about math. After all they still say that Jehovah reads hearts and a few flaws in their doctrine did not hold Jehovah back from anointing the modern day Witnesses as they celebrated birthdays and the big sin of Christmas and got involved in fighting during WW1 which led only to a hand slap of Babylonish captivity and imprisonment of 8 of their leaders after the war but no losses in salvation for those trangressors.
They have been very inconsistent to say the least! In holding to the idea that all those Christians before they came on the scene were apostate and didn't get the reward of heavenly life and that their religion was a sham in the eyes of Jehovah.
I think they will have to make up some new explanation and scrap the 1935 cutoff date and quite possibly discard the 144,000 literal number as the date 2014 approaches just to make their argument even remotely plausible and thus keep them in existence for how ever longer.
I see some serious changes in the not to distant future which will mean losses either way.
They will just need some younger and newer blood on the doctrine making body(GB) to keep the loses to a minimum because these old farts are just not up to it with their blood starved brains they are way too old and totally out of touch with reality. They will still be against education though right to the end because they don't feel good surrounded with smarter JWs to feed bull shit to.