I don't think anyone here actually believes Trump will be impeached. He could serve full term (or two), die of age/sickness/general bad health, or resign. I do not think he'll ever let others take him out. He's too proud for it. Out of character. They can try but it will not work, especially with Congress being majority Republican right now. I believe that if he goes it'll be:
A. He'll resign. This is, imo, only possible if his health begins to deteriorate or Mueller does have enough dirt on him. This could be advantageous for him as he could resign and claim victory over the Dems and "corrupt" Republicans and say the media took him down. This could build up big support from his group.
B. He'll die in office. He's old. Unhealthy. I think he could serve a full term but I think the stress of the WH and the attacks from the media will wear him and could actually kill him if he successfully wins a second term.
C. He'll serve full term and quit. I do think this is more likely than many think. And I do believe he will die if he gets a second term. It'd be irresponsible for his supporters to let him stay when they could easily find someone similar like Trump Jr to take lead.
D. He resigns because of Democrats. Now I believe this scenario will only happen if he wins second term. Because while I do think the Dems will win majority in 2018, I do not believe it will be a significant lead due to Dems not having a clear message right now. Right now I see them as the party against Trump, which is not a good thing, especially if you want to win parts of the south back. I think by second potentially term, the Dems will have a stronger message and win a large number of seats, which will allow them to impeach him, in which case he may also resign. It would he in the Democrats best interest not to impeach him though