Even if Elphicke, at some stage in the future, is convicted of the charges he faces, it will probably be well after the next General Election. As someone pointed out, the trial is unlikely to finish until way into next year.
A recall petition is another matter though, and I could see leave supporters in Dover demanding an MP who will back the PMs approach to Brexit, particularly with such a slender majority now.
Taking a quick look at past results, the Tories have held the seat since 2010 with a reasonable majority of between 6,000-8,000. However, it was a Labour seat under Blair - this is very interesting because the Lib Dems have done very poorly in recent years, however, if there is a more centrist core, they could spike. In 2010, the Liberals received 8,000 votes - so it's not a given that they would be out of the top 2.
It would be a real test for Labour under Corbyn's leadership because they really should be contesting this in any other circumstance.
However, the Brexit Party could have success too because UKIP won 10,000 votes in 2015. In the same year, the Conservatives won with 21,000 and Labour came in second with 15,000.
This could be absolutely fascinating given the political makeup of this constituency.