The worst thing a government can do is enforcing KYC for this type of venture. But even that would be a big upgrade from the current paradigm, which requires both KYC and very specific connections to even be able to invest in ventures. I'm assuming that both types will coexist in the future - coins with KYC and coins without KYC.
Depending on how regulation happens, companies might also just start their ICOs in specific countries that don't require strict KYC rules and thus attract more investors. In either case, governments and tax collectors are in for a ride... Very curious to see how this plays out in the coming decades.
I'm hoping that tax will just become voluntary and will be used in a transparent way that will make people more likely to pay taxes. If people knew that their money gets spent in good ways they probably wouldn't evade taxes in the way they do now. But most of the tax money gets wasted on bullshit, so it's no surprise that nobody wants to pay them.
Yes, indeed there are interesting times ahead of us. I also think that regulatory heavens for ICOs will emerge sooner or later, most likely candidates are Carribean or Channel Islands. Isle of Man and Gibraltar, two Meccas of online gambling, seems to be taking the lead:
https://www.coindesk.com/icos-welcome-isle-of-man-to-unveil-friendly-framework-for-token-sales/ https://www.coindesk.com/gibraltar-regulate-bitcoin-exchanges-possibly-icos/Incidentally, this is something that all regulation is good because it weeds out scammers guys, dont realize: the stamp of approval from regulation authority doesnt mean squat, unless you are pretty sure that the regulation authority does its job properly and does not hand out licenses to anyone willing to pay for it.
As a side note, particular government can do much worse than enforce KYC. For example, government can ban ICOs altogether. Or it can ban public ICOs as China has done recently. In China companies are not allow to sell tokens to general public, but are still allowed to raise money from accredited investors (which is very similar to the old system).
You can't ban ICOs though, since you can just move the ICO to a different country that doesn't care or did not ban them. It's very easy to set up companies elsewhere, so this approach is pretty much meaningless.
The best bet governments probably have is to suck up to crypto investors and to make paying taxes something desirable for the tax payer, otherwise people will just laugh at regulation attempts if profits can be made while circumventing regulations.
And there are numerous countries that have no capital gains tax where people could easily move to (at least on paper) to realize their profits. It'd take a lot of effort, but it's nothing new and something that the elite has been doing for ages. Now it's slowly becoming possible for just about anyone with enough perseverance to do the same. Who knows what governments will end up doing though.