It may very well be only 4 this time...
Possibly if the left leaning media can gin up enough hatred, but then again the Dimocrat's attacks have been back firing pretty badly the last year or so. If Trump keeps bypassing the party elite in congress to try and keep his promises, he may be re-elected and the GOP lose control of congress. If congress pulls their head out and starts doing their job they could gain strength and possibly have their first super majority in a long, long time.