Major spoilers ahead for the seventh episode of The Flash Season 4, called "Therefore I Am."
The Flash has gone in a very different direction with its supervillain in Season 4, as the Thinker is a big bad without any super speed to make him a rival for Barry as the Flash. The Thinker, a.k.a. Clifford DeVoe, has been at least ten steps ahead of Team Flash all season, and they only caught up to him because he decided it no longer mattered if his identity as mastermind was a secret. "Therefore I Am" featured Barry's first showdown with the Thinker, and Barry at least knows his enemy now. The episode also delved into the Thinker's backstory, and it may have revealed just how Team Flash will be able to defeat him.
Team Flash did manage to rule out the possibility of the Thinker as a metahuman, but he was still affected by the particular accelerator. His attempts (with more than a little help from his doting wife the Mechanic) to harness the power of the exploding particle accelerator to power his "thinking cap" that would enable his brain to process tons of information backfired in a big way. Although he did gain the abilities he was looking for, he was permanently damaged, resulting in his own paralysis and premature death in the not-too-distant future.
The Mechanic was able to construct a special wheelchair -- that apparently can fly to allow the Thinker to venture out of his lair -- to slow the progression of the lethal damage. The result is a prolonged life for the Thinker; unfortunately for him, however, he'll waste away if out of the chair for too long. Basically, if Team Flash can somehow damage the chair beyond repair or isolate him without his chair, the Thinker could simply waste away and die. His brilliance is so incredible that it practically qualifies as a superpower, but it won't be able to save him from physical death.
Of course, there are a couple of other ways teased in "Therefore I Am" that could lead to the Thinker's defeat and/or death. Despite losing his touch with humanity after gaining his incredible abilities, he still seems to love his wife very much. If Team Flash is able to somehow use the Mechanic as leverage, the Thinker could potentially become sloppy and make enough of a mistake to allow the good guys to gain an upper hand. Team Flash might have to go pretty dark to use her as leverage, but "Therefore I Am" indicated that Barry is willing to go to extremes when it comes to the Thinker.
Alternately, if the Mechanic somehow comes to believe that her husband has gone too far and is doing more harm than good, it's possible that she could try to help Team Flash. Such a betrayal could damage the Thinker's grasp on events enough to throw him off. His arrogance could also take him out of the game. While he does have every reason to believe that he can outsmart even the brain trust at STAR Labs, his arrogance could backfire on him. All it might take is one mistake of the Thinker assuming Team Flash can't do something, and the game could change. We'll have to wait and see.
The Thinker probably won't show up next week, however. The next episode of The Flash will be one leg of the four-part "Crisis On Earth-X" crossover, which kicks off on November 27 at 8 p.m. ET on The CW. Don't forget to check out our midseason TV premiere guide and our rundown of 2017 TV cancellations.