It depends upon the 100M accounts.

That would obviously spread out the distribution among a lot of accounts. The question is what are those accounts doing? Were they accounts people signed up for, played around a while, got a SP, and left. If that is the case, then it is akin to SP that is null. It is inactive.

If, however, those accounts are active, such as on other applications, then you will see a slow earning of SP and the reward pool really spread out.

This is why people such as myself, @exyle, and @preparedwombat mention how it will be harder in the future to earn STEEM via content creation.

Just do the math...a 500K SP inflation per week divided by 50K active accounts or 500K SP inflation (it will be less as the rate falls each year) divided by 100M active accounts...

In the later scenario, you can see how hard it is to earn SP.