IMO the gravity of Trump's offenses are too great not to result in an indictment, and this first "Episode" laid a firm foundation for bringing charges...he clearly had "Corrupt Intent"...so, yes, I believe the DOJ will indict him...
As for Biden or the Mid-Terms...there are a lot of other issues that will come into play...i.e. the economy, inflation, Putin, Roe v. Wade, etc...but these hearings could hurt GOP candidates if they continue to support Trump...especially in "purple" districts/states.
Since there are five more episodes to go, the hearings won't likely be forgotten until July, unless the GOP can come up with an impressive distraction...even so, 'loyalty to Trump' vs. 'loyalty to Democracy and the Rule of Law' will become a bit of a "shibboleth" in the Fall...how much so will depend on the quality of the Dems communications.