Impeachment is a useful tool in the toolbox, in terms of dealing with aproblematic president. A criminal should not be able to serve as a president. For example, the lIkes of President Richard Nixon would probably have easily passed the impeachment process. The impeachment process works easily enough, though still arduous and not truly that easy. It works and it is plausible, even if it hasn't been completely been done all the way and rarely finishes the two step process, which successfully removes the president from the office of presidency.
At the beginning a president's impeachment is Brought before the lower house of the Legislature, the house of representative, or congress. The 450 member house of Representatives vote on this impeachment. It only requires a simple majority, 51 percent or over. Most of these are partisan first step impeachments. Technically speaking, if it passes congress, this president is impeached. He is not however removed from office and may serve his term. Voters can then vote him out if no further action is taken, or if they still approve of him can vote him back in to office. After the House of representatives impeaches the president, this process then goes to the upper house of the Legislature, the senate. The senate then completes the impeachment process. This second step would convict the president and remove him from office simply or also disallow him from ever serving his country again by allowing him to hold government positions. It all depends on what the senate ultimately decides. The fate of the president is now in their hands. This fate is more difficult to pass. While the impeachment charges in the lower house can be more so political or not as serious as the upper house, I would think for a real conviction to happen the case must be pretty serious. It is not completely impossible to remove a president from office It has never officially happened, though it may have if President Nixon would have stayed in office for the two step impeachment to happen. Of course, he didn't desire this outcome so he stepped down from his office and resigned. It would have to be a bipartisan vote and decision. For this to happen this senate hearing which is usually but not always chaired by the Supreme Court chief justice must obtain a 2/3 super majority. Unless the opposition party has that many senators in the senate, the only way is to have it be serious enough to convince at least some of the members of the presidents own party. It is not impossible and it can be done. This process is actually th same for any government official. It would work just like this for any federal office holder.
I think just because the political climate in this country is more polarized it does not mean that it is impossible, ineffective, unreasonable, ETC… This polarization shouldn't and doesn't invalidate impeachments. I think if the case can be proven very clearly without a reasonable doubt why a office holders should be impeached and you are able to convince the presidents party that he doesn't deserve to be president then by all means, use it. It can happen that a president can be impeached or even be removed from office. I think it requires especially these days a strong argument. Of course, it may not have to be a severe crime, but this rationale has to be widely accepted enough so that it can gain a super majority in the senate if the country wants to convict and remove a president. If not, it has to be powerful enough to gain a majority vote in the senate. It may be a unfair partial impeachment. Think ultimately it has to be a fair conviction and a fair bipartisan vote in the senate, because it has to be a super majority I think ultimately if you want it to succeed and to actually remove a president, it has to be fair even if it's political, and not a simple partisan polarizationn.
As I stated In the beginning I do think it is definitely a plausible and reasonable tool to use against a president, even in this polarized day and age in 2018 and beyond.