And then why does England need 18 20/20 teams when IPL does so well with just 10 teams.
County members are already questioning why they should pay for marginalized competitions (Metro Bank) and reduced number of games (Blast), along with county games being pushed to months when you're not likely to want to sit outside all day.
The Hundred will be reformatted to T20, that seems an inevitability. Then expanded in terms of number of games, and possibly add in the two international grounds without teams (Durham and Bristol). Same model as the IPL basically, that started with 8 teams and 6 weeks, now 10 teams and just over 2 months. That would mean expanding to cover basically all of July and August.
County cricket, and possibly international cricket, would be fucked. You'd end up with county games being like the Metro Bank now, best players missing and playing at outgrounds.
Even international cricket is at risk. People keep saying it won't happen but look at the new owners of Manchester Originals. They own an SA20 team alongside their IPL team. They're bound to go for a BBL side when they are up for sale in the near future.
With a bit of a tweak to the calendar you could have December & January for BBL, February & March for SA20, April & May for IPL then July & August for the reformatted Hundred. Do you really think those franchise owners won't be offering year round contracts to the best players? National boards will be needing to get permission for players to take part in internationals.
There's even a nice gap so they can prioritise annual T20 tournaments. Depending where in the world you're having it you can go November in Aus / NZ or June in India or England.
/rant
Edit: forgot the CPL, that's September covered, and there's also the thing in the UAE, move that to October / November and you've got franchises year round under the same ownership.