It is theoretically possible for him to overrule their decision, but highly unlikely.

按理说他可以否定他们的决定，但是可能性很小。

《牛津词典》

It's theoretically possible, but highly unlikely ever to happen.

这从理论上说是有可能的，但是基本上不会发生。

youdao

FM radio: Another one that was highly unlikely, but again, we know there are some who want it.

调频广播：另一个非常不切实际的期望，但同样的，我们知道有些人希望新操作系统中有这个功能。

youdao

There has been, at various times, idle speculation about a wide-range of intriguing but highly unlikely potential suitors.

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Asked if he believed Google could change tactics and restrict apps such as Home, he said it was theoretically possible, but highly unlikely for Google to do a "180-degree change" in its stance on Android's openness.

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The latter is certainly possible, but also highly unlikely.

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