...if the area can support the bees with what they need, then it should be fine.
yes, it bodes well for your location that you have unmanaged 'wild type' or feral bees doing well near by.
In my opinion, having these hives around yours will be a bonus...
a huge bonus in my opinion. especially if it turns out those colonies have been surviving unattended for many years.
So next spring regardless of space the bees will most likely swarm.
agreed. it's likely that those colonies have been issuing swarms as long as they have been there. if there is an abundance of wooded lands around the area is probably inhabited by a nice meta-population of this surviving local strain.
My thoughts were that these bees seem to bee thriving therefore they may naturally more defensive to the beetles and mites?
that is a safe assumption.
Will having 4 or 5 very large wild feral hives in close proximity to my personal bee hives be a problem.
actually the opposite is more likely the case. if you indeed have a local strain of surviving wild type bees then your imported bees (depending on the source) can pose more of a risk to the local population than vice versa.
this is especially the case if your colony suffers collapse late in the season and the local bees end up robbing out your hive. if this happens then any particularly nasty pests and pathogens (primarily mites and viruses) will end up being brought back to the unmanaged hives and threaten them.
this is easy enough to prevent but sometimes challenging for a first year beekeeper since there is so much learn when just starting out. colony losses are typically higher for beginners with losses to varroa mites being the most common reason.
please consider taking measures like having an experienced beekeeper help with with mite monitoring and treatment if necessary. consider installing a robber screen on your hive and be prepared to put a stop to robbing should it start.
for next year prepare a number of swarm traps and place them prior to the start of swarming season for your area. it's very possible that you have access to some special bee stock that may be much better than what you can buy at the bee store.