In many ways she's the natural go-to - she's well-spoken, fairly young and fresh, and remains untainted by Westminster scandals after having rejuvenated the Tories up north. Her LGBT credentials also help if the party are looking for a fairly liberal, modern leader.
But I do think she'd face a lot of problems. For one, she's spent her entire time as a politician in opposition and as a result she's become very good at generating soundbites without having to actually defend government policy at all, which is always much tougher than constantly being on the attack. She tends to get an easy ride from the media as well - when she's on QT for example she tends to be the sole Scottish representative, and as a result often gets away with exaggerating certain truths without being stringently called out on them. And as of yet she's completely untested at Westminster - it's a very different environment to Holyrood, and she'd have a tough time trying to manage an already fractured Westminster party when a lot of them would view her as an inferior who's been parachuted to the top without notice, especially since she's an ardent Remainer.
Also she's Scottish. And so would be expected (you'd imagine) to take a Scottish seat if she wants to appear at all credible up here. But the problem is there's not really any such thing as a safe Tory seat, and so if she wants to remain as an MP up here then the Tories would have to rely on having a PM could be unseated in any strong swing against them.