Having been around long enough to ride the 80+% drop when Gox collapsed, I don't think it would be as dramatic as that. I suspect a larger overall percentage of Bitcoin users were involved with Gox in 2013/2014 compared to the overall percentage of users who store wealth in stablecoins today (although I could be wrong). I would also hope that regulators would announce a sensible timetable, well in advance of any major changes, to prevent panic. Pretty confident that any fluctuations with Bitcoin's price would be short-lived and would probably recover fairly swiftly.
I believe the far greater harm will come to those who opt to continue holding stablecoins from this point on. And, to be perfectly blunt, I'm going to have little sympathy for anyone who gets burned when something negative happens there (and it is definitely a 'when', not an 'if'). The warning signs have been there long enough for even the most blinkered person to take notice. They looked sketchy even before the regulators took an interest. I'm of the view that people who freely choose to continue holding vast sums of these corporate IOUs, despite all the mounting evidence as to why it's a terrible idea, must have a mental impairment. There's no other logical explanation for it. All gamblers lose eventually and that's what stablecoin holders are. Get out while you can.
In 2013 - 2014, the cryptospace’s total market capitalization might not be more than $2 billion, the daily volume might not be more than $1 billion and regulators were not very active. Mtgox’s systemic risk might not be as large as Tether’s present systemic risk. I speculate a liquidity shock of losing Tether will have much more impact than losing Mtgox on 2013 - 2014 and the recovery might be longer.