My understanding is that

1. Our rocket / propulsion technology today may be cheaper (thx largely to SpaceX), but it doesn't really necessarily provide MUCH more delta V. Meanwhile

2. Voyager launches relied on a once-in-a-blue-moon (not quite once in two centuries) alignment of various planetary bodies to give a spectacular orbital slingshot boosts.

So my limited understanding is that we can't really overtake voyagers very easily. Whether our current technology coild be made more reliable in the long term is another good point of discussion :-)