what are the dangers of one party holding the media, the House, the Senate, the Presidency, the Courts? stop thinking about Trump for 2 se. ?

Dictatorship................

The U.S. Constitution LIMITS the power of government and keeps it in the hands of the people.

If the DEMOCRATS have enough power, they can essentially modify or destroy the constitution. They are the party of MOB RULE.

Republicans are doing the best they can to PROTECT the constitution.  They are the party of Lincoln and the party that recognizes the U.S.A. is a REPUBLIC under rule of law.  (Say the pledge of allegiance.  It does NOT say "and to the democracy" for a reason.)

depends on whats going on

The Republicans and Democrats ARE one party. Trump is the only major politician who stands against the one party system. 

It doesn't matter as long as whats-his-name no longer occupies the white house.

It means the government can be used to overturn the rights of the people, the traditions of the country, and reset the USA into something people cannot recognize anymore. That is why so many Democrats left the Democratic Party. They don't recognize it any more. The Democratic Party is Marxist and very confused in it's ideology, which makes it dangerous to the people who voted for it.