I see two things come out of this:
1. Companies selling their B2C services digitally will be paying both their sales (or VAT) AND their corporate income tax in countries where their customers are. This will be a benefit for countries with large markets and leave smaller countries where the companies are headquartered wondering what the value of these companies to their economies is.
2. A major problem for digital businesses will be the fixed costs of compliance. I suspect that a lot of side-projects and lifestyle businesses won't see the light of day on account of how expensive it will be to keep them running for years while they build up revenue.
My hope is that these rules will only apply to large multinationals but somehow I doubt it - governments are unlikely to leave money on the table and will likely use this opportunity to expand the scope to include smaller businesses as well.
Tracking country of origin for every online purchase and grouping them in order to pay international taxes would be an absolutely ludicrous requirement. No matter how low your opinion of the G7 is, they're not that dumb.
It might be a bad idea but it's not beyond the realms of possibility.
Enforcing fair taxation is not a bad idea, making it awkward is.
It's extremely common even for small software companies to have offices across the world
Potential for having to pay income tax in countries you have customers in, sometime in the future, is > 0%.
Edited to add...
The article states: "the rules will aim to make companies pay more tax in the countries where they are selling their products or services, rather than wherever they end up declaring their profits."
The following scenario is unclear to me: A software company based in a European country sell their SaaS product to primarily US customers. The majority of their profits are made with US customers, but the company has no office presence in the US. Does that mean the profit from US sales is subject to the rules of this new tax law? (I assume not, but I could be mistaken.) I assume this law only applies if the company has a physical presence in the US. (But now wondering if my interpretation is correct!)