Australian here. Yes, we have a tax treaty with the USA, so that we don't have to pay the IRS as well as the ATO. Steam reports their cut to the IRS (~30%), and we report our cut (~70%) to the ATO.
If we haven't filled out form W8-BEN (or if the treaty was cancelled), then Steam only gives us 70% of our cut, and withholds 30% to the IRS (meaning we'd get 70% of 70%, or 49% of the retail price, and then also pay up to 30% tax on that 49% to the ATO, meaning we'd get as low as 34% of steam's retail price...).
I don't know what the US stands to gain by making doing business with Australia harder, so I wouldn't expect any President to rip up that treaty... But yes, that would harm our industry as the US is a major market.
We would likely get around it by registering our companies in Delaware and paying zero tax to the IRS anyway :P -- Part of the reason for these treaties is actually to crack down on tax avoidance by sharing information between nations.
FWIW though, conservative parties always say what the working man wants to hear, then do their best to protect the interests of the ruling class while expanding the under-class, which includes undermining the stability of the working class... So yeah, this ain't gonna happen. Despite what anyone said during the campaign, expect life for the middle/lower classes to remain just as unstable as before, if not become more unstable... and expect offshoring of manufacturing, corportate tax evasion, etc to continue...
However, the markets have reacted very negatively to this result... The Australian stock market was devalued by something like $50B today!
If our economy crashes more than the US economy (or the US actually strengthens... ha!), then that's good for game developers here, as our earnings in USD become more valuable.
If our economy crashes less than the US economy (or we strengthen), then that's very bad for us, as suddenly our USD earnings are not as valuable.
When the US went into recession due to the 2007 crisis, Australia was actually just fine thanks to good economic management here (unlike Europe, ouch, bye Greece)... Which meant that suddenly our USD earnings were only worth something like 60% of what they used to be worth. This was apocalyptic for our games industry. Every single AAA developer that I can think of closed down during that period and thousands of jobs were lost.
So here's hoping that the markets are wrong, and a trump presidency is actually good for the US economy (ha!)...
