If btc is legally accepted in all countries then huge number of investors will increase. and the use of btc in various fields will increase.
what is your opinion about this?
That should be a big movement for every government but I am certain this will not come sooner because there are even other countries that has Banning rules against bitcoin as they are questioning the capability and the decentralization of the coin in which did not goes towards their policy and targets.
First you have to explain in detail the meaning of BTC being legally accepted, accepted as an investment vehicle or as a means of payment? If it is accepted as an investment vehicle or digital asset, maybe this makes sense and in the future there will be regulations governing this issue. but if it is accepted as a means of payment, this seems impossible because it is impossible for there to be any other legal means of payment other than fiat currency.
I believe that once Bitcoin is accepted as investment materials then being accepted as payment will follow because it is not for government to decide who will accept bitcoin but it is from the business sectors(or some government transactions of course)