While the surprise of this fleet lasts, yes, for a week or two. After that work-arounds of various sorts will occur, from convoys to evasive routing based on accumulated intelligence reports which will see imports begin again.
No doubt all sorts of back and forth. But, a German navy that has not triggered USW is a German navy that hasn't made the fatal mistake of the war yet either, and should be contributing positively to the CP war effort by way of increased supply from the Americas. So strategically sound, given that USW backfired in the land war bigtime by adding the AEF and US industrial might to the equation, while a chippy but honourable campaign at sea would favorably influence neutral opinion.
I said limit freedom of action, not defeat in battle, in fact I specifically said that the 14" Kaisers would drill any of the forces the RN had in the Atlantic in Nov 1914. However doing that would mean having to drive the ship at battle speeds with heavy fuel usage and expend heavy ammunition, both of which are difficult to replace in the west Atlantic, so the Admiral would have to think long and hard about his entire before entering these target-rich areas. Is his task to defeat some ratty old warships, or sink merchant ships, and does sinking these warships help his mission by giving access to shipping concentrations or is it better to sweep less busy areas that are more easily avoided by merchant ships? And what about the risks to his fleet, what if the ratty old pre-dread or armoured cruiser gets a good hit on one of his ships, does he abandon it or endanger his force by trying to rescue it? How much ammo and fuel does the admiral want in reserve to get home, perhaps in a running fight with the GF?
I'd want to game it a few times before making any conclusions on the best use of a longer ranged squadron. A ship with 16,000nm range would require something like 8,000 tons of fuel. A Kaiser could only carry 4,000 tons, so I'm thinking the ship has to be about 30,000 tons as built with lighter armor and no increase over historical armament to pull it off. Maybe 3/3/2 = 8x14" in 3 turrets might be feasible. With that type of range it could operate around Iceland for a month without refuelling. (The other units in question, the German BC's, were only 4500-5500 nm cruise range, so were also defectively designed, at least for Germany's strategic needs in a naval war including Britain).
In terms of what to do with a dreadnought too damaged in battle to try to return to port in Germany, or even continue to function on the high seas, I would surmise a number of options were available. First, to strip it of supply, (food, armament, ammunition, fuel, etc), scuttle it, and use its crew for prize crews and such. Second, to not scuttle it after stripping it, but intern it in a neutral port loaded with prisoners and wounded. Third, to pick an enemy port and sail right in for a direct assault right in the harbor, landing to burn down the port facilities, and scuttling the ship, then evacuating the landing forces to the squadron and leaving.
In terms of potential missions, one profile would be to operate against the GIUK blockade line to allow ships to sail through to Norway or Germany by sweeping up units (AC and AMC) on patrol. One useful capability there would be the capacity to move into the Artic icefields, (coaling in the ice would be millpond calm) but I don't recall the HSF being sufficiently unlazy to have built icebreakers or even bothered sending explorations to the Artic regions to examine this purpose pre-war. (Could a ship traverse Greenland around its northern shore and enter the Atlantic/Norwegian Sea from the north? I do not know, and neither, I bet, did Tirpitz).
A second possible mission would be classic commerce raiding, either by sinking merchant ships or putting prize crews on them to return them to port. Could a prize crew sail a merchant ship into an American port and sell the products? What are the chances a prize ship could run the blockade to Germany or Norway with its cargo, either escorted or on its own?
A third mission would be to attack an available inferior Entente squadron overseas to cause naval attrition, or even to launch an assault on an Entente port, even with an amphibious element, in order to force Britain and France to move large numbers of troops and artillery overseas to garrison their ports.
A fourth possible mission would be to take control of the sea approaches to neutral ports where German shipping is bottled up, such as New York, so that this shipping can move to sea and return to Germany, (or provide supply to the squadron). Or, perhaps, to send prize ships to sell cargo in exchange for supplies useful to the squadron or Germany, if this is possible, (neutral attitude and policies).
A fifth mission - and this is the one catches my fancy - would be to focus on the undiscussed, unmentioned Archilles heel of the entire Entente war effort; its nitrates supply. Germany had the Haber process. The Entente did not. Much if not all its nitrates came from Chile. What if a German squadron were to dominate the waters off Chile, or interdicted nitrates exports, like Spee did briefly in November 1914? Even taking the nitrates to sea and scuttling them prevents the Entente from getting them; nitrates on the bottom of the Pacific are not explosives in British artillery shells, right? Could nitrates even reach Germany, either direct from Chile, or via the USA? 50,000 tons per year to Germany and another 50,000 tons prevented from reaching Britain per year might be a war winner for the CP.
Its these sorts of mundane things that ruin the magic ship theory. A big sexy raid doesn't have the effect of months and months of grinding uboat patrols, mining, tboat attacks etc.
Where did you arrive at the idea it was one or the other? In the war the HSF had the doctrine that the submarines needed to screen their capital ships because they were doing nonsense make-work sweeps in the North Sea looking for mythical RN inferior squadrons to sink. Discard that doctrine and the U-boats and TB's can do their thing while the modern elements of the HSF do their thing, and the older units (Helgoland, Nassau, PD's) do the coastal defense stuff.
The North Atlantic is 41,000,000 square miles and an area can be repopulated with ships the day after it was swept by the dragnet.
Any disruption in sailings cascaded through the system for months as delayed shipping performed no useful task while idle, and then too much all piles into port at once.
Of course these simple sums don't mean much in the real world, some of the area will be empty of everything except icebergs while other parts will have the enemy as well as targets in it, forcing the German Admiral to make some potentially tough decisions about the profitability of his actions.
So long as Hipper's squadron is not caught and sunk, it's creating a massive headache for the Entente war effort. Far more than if it were sitting in a German port doing nothing. The coaling requirements alone to stock overseas ports to accommodate big Entente dreadnought squadrons would be hundreds of thousands of tons of shipping. Three hunting squadrons of 12 dreadnoughts each would burn maybe 150,000 tons of coal per month!
None, its the old John Byng anecdote. However Tourbrige and Milne were both court martialed for allowing the Goben to escape, and despite being acquitted because their orders were ambiguous Milne was put on half pay and Tourbridge shunted off to a shit job, so the message is clear.
So no one was shot.
All in all the 9 ships you postulate will maybe significant temporary local impacts while at sea but these will be limited as the British employ mitigation efforts, until the RN inexorably tightens the screws on them and 100 ships defeat 9.
Sure, the British just phone the Kaiser in Berlin, explain they need to peel 36 dreadnoughts to overseas stations for up to 10 months in hopes of a causing a battle, could the HSF not bother us in the North Sea in the meantime?