To answer the original question, they'll stop when they've finished alienating the very people you'd think they'd be trying their damnedest to attract.
With the political, economic and (field) sporting upheaval taking place in Scotland at the moment you have to wonder why any high net-worth individual in their right mind would move there.
When it comes to raising income tax Scotland has a little over half the proportion of additional tax rate payers compared to the rest of the UK (0.7% compared to 1.1%). In round numbers that means Scotland has just 17,000 individuals who pay that additional tax rate. Not exactly a huge number - in fact you can forget Murrayfield as you could fit all 17,000 into Tynecastle! That same 17,000 contribute 13.9% of Scotland's income tax revenues, or just under £1.6bn per year out of a total income tax revenue of £11.3bn. For sure they may live lives detached from your and my version of reality, but that's still a tidy sum of money.
"Big deal", you might well say, "why should we care about those lucky ******** earning that kind of money?" As I see it this group probably represents those most likely to invest in Scottish estates since, let's face it, the quickest way to end up with a small fortune is to start with a large one and buy an estate in Scotland
So whilst changing Sporting Rates and offering Land Reform might sell well to the urban masses, for many of those high net-worth individuals with an interest in the countryside the odds are rapidly stacking up against investing in otherwise non-productive land in Scotland. After all, the chances are you'll eventually lose it.
So what happens as those rich elite head off to invest their ill-gotten gains elsewhere? Sadly more and more of the burden will have to fall on those who are already contributing a disproportionate share of income tax. Taxpayers with an annual income of between £20k and £50k already contribute 43.1% of income tax revenues in Scotland compared to 35.6% in the UK as a whole.
After more than 20 years of stalking in Scotland I've often dreamed about retiring there, as the people, the countryside and the culture take some beating - and I say that as someone who's been lucky enough to travel the world with my job. But with the way things look at the moment that dream is fading. I'm sure a lot of those in the SNP won't be losing sleep over that, not least that tiny but vocal minority who seem to have more than enough of their own "bile and bigotry" to heap on anyone unfortunate enough to have been born South of the border. Whilst England clearly has its fair share of similarly misguided individuals, they are not quite so common amongst our parliamentary representatives
The numbers, by the way, are there for all to see at
http://www.parliament.scot/ResearchBriefingsAndFactsheets/S4/SB_15-72_Income_Tax_in_Scotland.pdf