You can still technically use Bitcoin without third party services. The only thing you would be required by law to do was to file taxes. If you're doing that, then there's no reason why you can't just use Bitcoin without any other third party.
You can use peer to peer exchanges. The only limitation would be when it comes to escrowing funds, usually that's required by a lot of users here. There's no easy way around that either. Although, at least with that you, and the other trading partner can decide what escrow among you, and you aren't forced into one. For example, using exchanges is usually limited to your geographical area to some extent.
While it's possible to avoid third-parties when using Bitcoin, you'll face a number of difficulties that will prevent you from getting the "full experience". For instance, decentralized exchanges don't have the same liquidity and ease of use as their centralized counterparts.
First of all, I'd argue that the 'full experience' doesn't involve fiat transfers. The 'full / ideal Bitcoin experience' would be earning and spending BTC without need to exchange.
Secondly, liquidity on centralized exchanges is often completely faked or meaningless anyway. You gain nothing as a Bitcoin user, whether there are 1000 day-trades per second or 2000.
On Bisq, I can usually find or create an offer which is taken within a few hours (e.g. overnight), in the BTCEUR market. That's easily good enough.
There's also the issue of recovering your funds due to loss, hacks, or theft. Some centralized wallet providers have safeguards (eg: Coinbase) that would protect your Bitcoin against such undesired situations. That's because they're regulated and are insured in every way.
Actually, there are much more funds stolen from (by (!!)) centralized exchanges due to random claims of
'taint' or similar. Never had such issues on Bisq, on the other hand.
Decentralized P2P exchanges don't need regulations like the ones you describe, as they don't even hold your funds. Cut out the middleman!
By holding Bitcoins yourself, you'd be on your own if something undesired happens with your holdings. The good thing is that you will gain more privacy and have complete control of your funds. I guess you're going to have to evaluate the advantages/disadvantages between using Bitcoin with third-parties or all the other way around. With all of the tools we have at our disposal, I don't think privacy will cease to exist during our lifetimes. Just my thoughts
Why even use Bitcoin if you don't hold it yourself?
I wouldn't worry about governments increasing their regulatory efforts against Bitcoin as long as it remains decentralized. Just my opinion
I would; if they make it a crime to own BTC, it will become very hard to meaningfully use it, acquire more of it or sell it. No matter whether the nodes are still decentralized.