It is set in 2048. Only about 0.05 BTC reward per block by then 
Where is it written that fractional coins will be mined. I see people say this, but it is not my understanding of the plan for Bitcoin or how it is supposed to work.
The network only works on satoshis (1E-8 or 0.00000001 BTC). The block reward began as 5,000,000,000 satoshis (50 BTC) and it will be halved every 210,000 blocks (~4 years) until it reaches 1 satoshi and then go it goes to zero.
https://en.bitcoin.it/wiki/Controlled_supply
There is nothing special about a "whole Bitcoin" everything on the network is recorded in integers as satoshis.