Yes i know the US has a monster of a large and very powerful armed forces with many capabilities .but the gaps which NATO has in its capability (with out the US) could be closed in the future if these areas were looked into in a serious way through cooperation of some of the leading members like the UK,France,Germany.etc. I believe this is a must and a priority has the US turns to focus on the pacific-asia theatre and the possible future threat of china,north korea etc , alot of its armed forces will be changing its forcus and will be redeployed, so other than a major conflict kicking off in europe i believe the US with be taking the back seat more and more and the rest of nato must adapt to this,
Nato needs to regroup and refocus its strategy , its seems the whole defence objective was based on a war with russia thats passed but threats remain in the world , but the armed forces of nato members seem to reflect that old cold war thinking ,every member had its part in to play in this old strategy , for example, the royal navy was to shut the door on russian subs trying to get through into the atlantic so its whole fleet was basicly designed for that purpose. what im trying to say is that every one had there part to play, and the US had a big part which would of course be missed, i think changes are underway to rebalance many european armed forces but this will take time.