I'd still honestly say it's too far to tell. As we saw in the week of the formal inquiry so much crap was unearthed within such a short amount of time, giving the public new insights into the breadth of the Ukraine Scandal (which I can assure the Slav-Swastika having fella above me isn't just a conspiracy theory ) and was enough to sway public opinion to majority in favor of impeachment.
So, a lot of shit can still happen from now to then, but my best guesses is that the GOP controlled senate will do absolutely everything in their power to stonewall it, ignore their constitutional duties to be impartial on the procedures, and use their shady victory as a vindicated rallying cry in hopes of spinning the narrative into 'TOTAL EXONERATION' like they did with the released Mueller report.
From there, Democrats should focus on running that into the ground with their advertising moving forward. Highlight how little the GOP seems to care about the Presidential Abuses of Power, proclaim from the highest peaks how much of an absolute sniveling Coward Trump is for never even showing up to his own impeachment, and take the previous point along with his Tax Returns about how little Trump actually thinks about the laws and rules of the land.
Move the narrative into his Lawlessness, and run it with the same blind confidence the GOP puts into their own failed conspiracy theory bullshit.