If this is thrown out in the senate, can Congress keep voting to impeach him for other things he's done wrong?
Even if he's never going to be kicked out of office, it would feel better to see him finish his presidency with 15-20 counts of impeachment against his name.
As things stand the Democrats have changed tact. They're no longer sending it straight to the Senate for it to be dismissed by McConnell and Graham in a sham trial and Trump "TOTALLY EXONERATED" straight away.
They're going to sit on the articles of impeachment until they have a Senate trial process confirmed that will see Senate Democrats able to call all the witnesses into the trial and relevant subpoenas served for the missing documents and testimonies that Trump has blocked.
In the mean time there are cases moving up to the Supreme Court which should see Trump's blocking of subpoenas ruled unlawful which will put the likes of McGahn, Mulvaney, Pompeo, Barr and co in legal jeopardy personally along with any staffer working within any of the institutions within the executive branch who receive request for documents. The cases have moved up through the lower courts without any resistance so even with this supreme court it is unlikely that it will be overturned as it is diametrically opposed to the separation of powers defined within the constitution.
If they win this case then it's round two of impeachment articles which will be based around the Mueller investigation with subpoenas served for the underlying evidence and redacted content along with several articles around emoluments when Trump's tax returns are reviewed.
Between now and the 2020 election, there's likely to be another 3 or 4 trials with more and more evidence going on public record and Republicans up for senate reelection under increasing pressure to put on a fair trial to get it all over with.