Get a Scorpion if it appeals to you. Get it with a brace. Shoulder that brace if you want to do so - it is currently OK (formally acknowledged by BATF as being so, right now) to do so. Enjoy it while you can.
The bump-stock was legal. Until after the Las Vegas mayhem and Pres. Trump instructing DOJ to make them illegal - which was done by causing BATF to redefine a bump-stock as constituting a "machine-gun". Presto! Now it's illegal.
And YES. This CAN happen with the "pistol brace". In my opinion, it's almost CERTAIN that braces will be "redefined" as stocks when we get the next Dem President. Certainly when the Dems once again own both houses of Congress AND the WH. But when that happens, we can also expect another AWB. Almost certain to include buying or selling - maybe even OWNING - most or all of the various assault pistols" such as the Scorpion, MPX, Stribog, AR-9, etc., etc. etc. that we currently enjoy.
Even things like owning a registered SBR are NOT guaranteed into the future. ANY policy, regulation, or founding law CAN BE CHANGED - when there becomes political will to do so.
My point? It's CURRENTLY LEGAL to buy, sell, OWN, USE braces on pistols. Today is TODAY. There is no real way to confidently predict what will happen to what part(s) of private gun-ownership in the years as shifts occur in pop politics and in political control in our gov't. The future gets murkier the further out you try to look. The only real prediction you can confidently make is that gun laws WILL change, and probably NOT in the direction gun-owners and fans want them to.
So... Go get it TODAY. Enjoy it while you can. As long as you can. In a very real and practical sense, braced pistols, like any other gun, are, like beer, more "leased" then "owned". Buy it if it's what you want (presuming you can afford to), and enjoy it. Don't agonize and focus on how much you spent on it today nor worry about whether you'll get more for your money with something else tomorrow. Chances are, if you buy a braced pistol, "black rifle", or even an SBR... you won't get your money BACK. I love great beer. I don't sweat paying good money for it. I KNOW that I won't get that money back. So I buy it, drink it, and enjoy it while I can! Same with braced pistols and other such things! I bought a braced Scorp. It's a blast! I'll enjoy it while I CAN!