I think it’s a nice thing to do if you want to. It’s a matter of choice - I know my mother regretted being pressured into naming my brother as [name]Jr[/name]. after my dad, but if you like the idea, and you both agree, then it’s great. Calling him a different name around the house, like his middle name, is also a good idea. Being a 3rd, there are a few nicer nicknames than “[name]Junior[/name]” for a 2nd: [name]Trey[/name], [name]Tripp[/name]… anything so long as father and son aren’t [name]John[/name] and [name]Johnny[/name], maybe [name]Jack[/name]? Big [name]John[/name] and [name]Little[/name] [name]John[/name] is also bad - my household growing up with my brother and dad was like that. Someone calls the house, and you have to ask them if they want Big or [name]Little[/name], it’s kind of gross and my brother got big eventually, so it wasn’t suitable for the long term. If [name]John[/name] is just a stand-in name, I do think [name]John[/name] and [name]Jack[/name] are a distinctive pair of names for like-named father and son, but if it’s not the real name you’re referring to, I think this is a good reason for one to go by their middle name, while carrying through a tradition of sorts.
Your son may not want to carry it on another generation or meet someone who is agreeable to that (us ladies like the names we like sometimes, so it can be a sticking point). That’s pretty much the only thing I can think against this idea. I don’t think 2 generations is a tradition, but 3 can be sort of a hard trend to deal with, it takes on more importance the further it goes, and can be harder to put an end to it, if one wants to follow their own ideas. I’m probably not very much into [name]Jr[/name].'s, myself, but I do know someone who is a IVth, who recently had a son, and heard about this issue about naming his son - I know this person in one isolated context, I didn’t even know his wife was having a baby (barely even knew he had a wife), so if I think of it, I’ll report back on how it ended up. My friend goes by his middle name as your idea went, he’s [name]Randall[/name], well, [name]Randy[/name]. At the stage were I naming someone 5th in line (to what?), I don’t know if I could say it ends here, but if it were a case of a potential [name]Jr[/name]., I probably absolutely would. You pretty much hold the cards on whether it continues or not, being just a 3rd so far.