Here are some facts about the availability of Bot promotion among some others:
No Bots in NBBA
Division 2
Relegating Bots: 2
Domstad Devils, Valhalla!
Division 3
Non-Relegating Bots: 1
PBC Verona*
Relegating Bots: 11
Grim Koalas, BuckNuts, Hunterkirualeorio, Denver Extraterrestrials, Savage Slammers, The Meatbusters, Yenkins Bombers, Tai'shan Crimson Eagles, Flying Cows, Midget Dunkers, Wine Country Boozers
(* means that a team has not gone bot yet, but will go bot before off-season processing if they don't log in.)
This means that:
There is no spots open for a D3 team to bot promote.
There are 3* spots open for a D4 team to bot promote.
There are at least 14 spots for a D5 team to bot promote.
This also means:
There are 2 D.III leagues that will not get a D.II demotee, giving a D.III league a 12.5% chance of not getting one.
There are 11 D.IV leagues that will not get a D.III demotee, giving a D.IV league a 17.19% chance of not getting one.