I'd say no,
my reason for saying it... when many get bored/semi-active the world would not stagnate like many worlds for the prime reason that the tribe can't afford to carry semi dead players and/or hold them for ages getting someone to hand the account over to(in full).
I think(this is opinion) if anything the huge families may reduce as time goes on. I don't think families(even allies) work that well here anyhow due to the support being for own tribe only. It may be interesting to see how innovative ways to cope with the settings are found, you know it will happen, I'm sure other people are thinking of ideal setups also.
In summation, I think it would be short term benefit, long term harm as the world matures. Surely if people wanted to play a 40/100/1000 tribe member limit, they wouldn't have started w34.