I'm going to start by putting a highly possible scenario in here which looks like what is bound to happen in my country. Here goes:
The Central Bank in my country has distributed a circular on their website and several news agencies have gone through it and broadcasted it on TV channels and newspapers. What the circular mentions the following - "The use of Bitcoins and cryptocurrencies as a form of Legal tender / accepting as a form of payment is illegal" By outlawing Bitcoin in my country to be used as a legal tender, no single brick and mortar store, or an online service will be able to receive payments in Bitcoin for the goods and services they sell. So now, people can either personally send and receive Bitcoins only for trading (like a derivative or a stock), as a gift or for any personal deals (a barter maybe) which doesn't attract the regulator's attention.
After this was done, the very same week (or I guess the week prior) several Income Tax departments were alterted to visit Cryptocurrency exchanges to collect KYC/AML details of investors to track taxes paid (capital gains for long term or taxed directly as Income from other sources under the normal tax bracket). After this, every High Networth Individual's who've invested in crypto's were sent a letter to pay their taxes for the profits they've made on cryptocurrency sales. I'm assuming even other small investors are also on their radar.
Right after all of those, last week, several private banks have restricted accounts of all cryptocurrency exchanges forcing them to switch their accounts into Government owned banks. Also, the Citi Bank group as well as another private bank have restricted their customers from purchasing cryptocurrencies using credit and debit cards. If you're assuming people can trade on LocalBitcoins, yes they can, but there's no saying as to when the Government can start a campaign to track the sellers and buyers on this website since most of these sellers make use of local bank transfers or 3rd party payment services and they're easily trackable to both parties accounts, unless ofcourse you take the high-risk of buying / selling face-to-face.
The regulators are already starting to brand cryptocurrencies as "Cryptoassets" and are attempting to give it a bad name by going to the extent of calling it a
ponzi scheme to scare off new investors who aren't aware of it.
Now, looking at all of these restrictions imposed, I'm sure there's a regulatory body formed to regulate all cryptocurrency exchanges in the country. With this, people can no longer buy or sell Bitcoins with ease, and they'll be tracked. Also, the coins bought can only be used as a derivate or a stock within the country and not for payments or buying your food due to the "not legal-tender" restrictions. So basically all investors are just relying on the price of the cryptocurrencies based on its value in foreign markets, which upsets me.
So in short:
1) They'll regulate all exchanges
2) They'll make cryptocurrenceis not a legal tender
3) They'll then call it a ponzi scheme as it's no longer a legal tender cause they've outlawed it and the price is purely the sole intension to invest or sell.
4) They'll tax your cryptocurrency investments as capital gains (20-30% tax maybe) or part of the tax bracket and call it a cryptoasset. [I honestly don't mind the taxation part of it]
5) They'll ask banks to block customers who buy/sell cryptos outside of the exchanges in the country.
6) They'll then launch their own version of a cryptocurrency so people will obviously use it since they feel the safety of "regulation"
Overall, this is how I feel they'll regulate it elsewhere as well. I think those who already own crypto and haven't bought it via exchanges but have earned it online and not sell it for fiat will probably be the ones who could buy stuff from foreign vendors and utilize it without attracting much attention for a short time. I think confidential transaction and future BIP's in Bitcoin will make it difficult for regulators to track funds.