[Kapitan]

If i am honest i don't think the USN wouldnt benefit at all in open ocean deployments by having these SSK's

Having been on many submarines in my time knowing some of the parameters they operate in they are simply too slow and too small to be able to keep with a battle group, as for coastal defense the 688's and Virginia's do an exceptional job and can be on station far faster than any SSK ever could.
To give you some idea a 688i running flank can travel the 2069miles in 54 hours and 45 mins roughly

33knots = 38mph (2069 / 38 = 54 hours 45 mins) (you can confirm it using the 6 min rule too)

The east coast is vast that's not including the Gulf of Mexico and also the West coast the practical reality is the USN's current set up is perfectly fine the coast line doesnt need as much protection as any major power that has that amphibious capability (China and Russia currently) are unlikely to start anything, plus this is no channel hop both countries are over 4000 miles away and would be intercepted long before they reach american waters.

You also have to look at the current operational requirements for the current fleet, right now the threat from Russia is minimal and any threat asset is likely to be limited to a spy ship off the coast or a single nuclear submarine lurking around looking at the current Russian fleet their conventional boats do not venture that far, you certainly don't see the operational deployments of conventional submarines like we did in the Cold war, most of the Kilo's now are kept in home or local waters such as Baltic Black sea Barents and North sea limited stints into the Med (from the black sea) and localized runs into the Pacific from the Vladivostok and Kamchatka bases.

A nuclear submarine can be on station longer has more availability and also can travel further and faster for longer than a conventional submarine the Type 212 although can remain submerged for 3 to 4 weeks at a time it does so at the penalty of speed, it also has a size limitation as the last thing you need is an under powered boat something the Australians keep finding out with the Collins class which is the reason why they are looking to replace the lot.

The AIP / Conventional submarines for the USN would only really benefit regions such as the Persian Gulf, which would rely heavily on foreign support, it would also require heavy lift ships to bring them in place because of the transit times (same with the UK Mine hunters based in Bahrain)
The only other group i could see benefiting from SSK's would be the Navy SEALs as a smaller submarine can get in closer to shore but then they have now got the ASDS which does this for them so again a system has already worked around it.

Back in the 1990's the UK Royal Navy faced similar issues budgetary restraint and also the lack of suitable enemy its the whole reason the Oberon class was paid off in droves and also why the Upholders didn't see out the decade like the USA the UK went all nuclear because you get more bang for your bucka platform you can send any where any time and your enemy did fear you.

1982 sinking of Belgrano put the Argentine navy back into port it took conks around 2 weeks to get to the islands, it took HMS Onyx over 6 weeks to get home.
When the Gulf war came in 1991 HMS Ocelot was sent to the Gulf however the war ended before she got there and was recalled.

AIP / conventional submarines are great for navies like the Israelis who don't generally deploy beyond their own limits but for a navy like the USN unfortunately there is no need for them.