It is very hard to see how the Tories could “win” an election next time, for several reasons.
Leaving aside the current polls which aren’t relevant, if a “no deal” Brexit happens they are likely to be deserted by Remain-inclined voters and if they don’t deliver Brexit by the time of the next election they’ll be deserted by many Brexit inclined voters.
But leaving all that aside, they’ve been in power wholly or in coalition for 9 years as it stands and the Brexit saga has torn them apart and left them seemingly bereft of energy and ideas. Added to which the current leadership battle is likely to be a bloody one, with many people with some justification asking why 100,000 people, many of them seemingly ex-UKIP entryists, are effectively being allowed to choose the direction of the next government.
Entryism by militant factions in the Labour Party gave us Corbyn and the same thing is now happening here.