1. Countries may start having bitcoin as another reserve.
Here we should not assume like countries will first declare bitcoin as legal tender. They may collect as much as bitcoins first and then unveil their stand on bitcoins later.
They won't. Bitcoin is a speculative assets and tends to have a very large fluctuation in price. The total market cap, or if we consider the actual market cap of Bitcoin is very low as compared to the markets of precious metals and other reserve assets. Governments can at best have a tiny percentage of it in Bitcoins and it is not practical.
2. Governments will prefer bitcoin as a digital asset rather than a payment system.
Bitcoin is created as an alternative to government controlled currencies, no? Why would we care what government prefers.
3. Technically bitcoin is designed to be having huge value.
Limited supply and halving are explicit characteristics of bitcoins to assume it is designed to have huge value. When one satoshi is valuing 1 dollar or 10 dollar then you will not transact BTCs multiple time a day. Maybe you spend bitcoins monthly once or twice. Because you are going to use bitcoins only for your life's big things and you will have other income stream due to those big things which has happened with BTC payments.
Bitcoin can be divisible even further, it's just a matter of protocol change. The day 1 Bitcoin = 1 Million dollars isn't going to happen anytime soon, don't worry.
I don't see the practicality of on-chain transactions solely for the fact that merchants can barely accept unconfirmed transactions and having a huge fees with most transactions. I see a future with lightning network and other similar offchain solutions taking the role of daily microtransactions and stuff.