That depends a lot.
And it depends on how the regulation will work and what does that mean.
If bitcoin will be treated as a currency and that's all there will be no problems. Same as declaring it a legal tender in the country.
The problem will be taxation.
Even now, if you buy something with bitcoin in most countries you pay tax.
I know because I paid in a restaurant and the receipt clearly mentioned the VAT.
So as longs as you buy from legal merchants and not from the black market you pay taxes, even without regulations.
People sometimes forget that bitcoin won't help you much more than cash if you're going for tax evasion.