why would ANYBODY think that T or ANY president can be impeached over their ability to pardon somebody? 
T can pardon Hitler, and I doubt that he can be touched. It is a president's prerogative to decide whom to pardon. For example, when Ford pardoned Nixon and Poppa Bush pardoned reagan's and his admin's treason, there was nothing that could be done. 
And I suspect that when mueller goes after trump for treason, I suspect that either pence or ryan will pardon trump before a full conviction can occur. 

And yes, T will be gone before Xmas. The real question will be, who will replace him. 
If they go for treason, then Pence will be included, RIGHTLY and ryan will be president. 
If they go for obstruction, which I think is VERY likely, then pence will be president. 
Regardless, both will pardon at least T so as to avoid their party looking as bad as it is.