It would seem to me that the 2nd charge will be immediately dismissed if it makes it to the Senate. Essentially, the Democrats chose not to challenge the subpoenas because they were on some artificial time constraint. That’s their problem, though. That does not entitle them to bypass the courts and enforce a subpoena.
This is a stretch, but consider...The Democrats are so full of hate they pass the second Article of Impeachment stating Trump acted to Obstruct Congress. Since the Supreme Court has already granted certiorari to the tax case, why couldn’t Trump’s team immediately move to dismiss the second Article based on the fact Congress did not exhaust it’s remedy on the subpoena’s: the Court.
That would leave only the first, the Abuse of Power. The Senate could dismiss as there is no underlying criminal statute that defines “Abuse of Power” in the criminal code. Since there is no statute, there is no “high crime or misdemeanor” as an underlying offense. Dismiss, case closed, the Democrats/media will try and state it was a whitewash, the Republicans can say because the Dems were in such a hurry to affect the 2020 election, they rushed to judgement and got it wrong.
It would also bolster the case the inquiry was nothing more than a political witch hunt since by their own admission, they knew the Court was the correct remedy, but since they knew Trump was likely to win re-election, impeachment was the only way to keep Trump from re-election.