Part of the success of Blitzkrieg OTL, as I understand it, was that Hitler did reckon carefully--in his own way, which was not the way of the General Staff or conventional military thinking generally--on the forces he would have to defeat, and mustered those forces he deemed necessary to do the job in advance. In general the Reich achieved victory on his timetable in the first few years of the war, for the most part. (It was aggravating that the British didn't call truce on the timetable!)
So--for Onkel Willie to save the timeline, if he doesn't want it to be just "Stupid Hitler had a blind spot for the greater strength of the Netherlands and thus his whole war scheme was blunted and France never fell"--and we've got beyond that already, with the statement that France did fall though they fight on from Algeria--then the only way to square it is to suppose that Hitler did indeed muster more total force for the Dutch wing of the general attack plan on the West.
Where would he have got it and when? The main wiggle room I can see is that with a stronger Netherlands, in the political climate of the 1930s (with France and Britain dreading a second war and so temporizing at nearly all costs) Hitler might have been able to get away with more mobilization of German construction and force-building sooner, since the foreign political actors who gave him latitude for a buildup OTL would also take into account that Hitler after all faced a stronger West than OTL, and would therefore be justified in their view at seeking stronger forces for Germany sooner.
But I don't know to what extent this is constrained by the limits of economic rather than political possibility. If, OTL, Hitler did already drive Germany to the utter limits of productive capability, then no amount of motivation, or latitude granted by the Versailles/League powers, could have given him more troops, tanks, guns, and planes than he had available OTL--if that were the case, he would perforce have had to delay the whole war to allow more time to build up sufficient extra forces to account for stiffer Dutch resistance.
Meanwhile of course the British, French, and ITTL the Dutch were themselves busy upgrading their own forces, so it becomes very chancy--Hitler is trying to hit a moving target--perhaps in this case his pre-war political timetable of diplomatic conquest (at a discount on account of his intimidating manner
) would be slowed, to keep from alarming the Entente powers too much and too soon. Meanwhile of course the economic woes of the Reich continue to threaten to destabilize the whole regime, meanwhile the world slowly climbs out of the deepest trough of the Depression, meanwhile Hitler himself ages and he might die at any moment--the moment changes. If Hitler could possibly get the war going on OTL's timetable, he would.
Since ITTL the delay does not happen, OW's timeline depends on whether there actually was margin for a harder push for more men under more arms before the war in the Reich. If there was, it is still an open question whether that extra drive might have tipped the balance of political opinion in the West toward the conviction that war was inevitable and it was better to stop Hitler sooner than later.
FWIW my guess is, yes Hitler could have pushed even harder and got more material and men for his plans by September 1939, and yes, the main Versailles powers would have refrained from doing more than they did to stop him, so I guess it is possible.
As to just what forces the Germans had better have sent in to win eventually, on the timetable given already, I have to leave that to those who understand the mechanics of combat a lot better than I do!
My impression is, first of all the Germans did attack with more force than OTL, and second that they were indeed delayed and somewhat more decimated than they reckoned they would be--add to that that it is harder to clamp down on the Netherlands ITTL than OTL, what with all the resistance that perseveres. So while France is occupied, it does take longer and the surviving French forces withdraw rather than surrender en masse.
Presumably there are dire consequences for both Dutch and French civilians caught under the nervous thumb of more insecure Nazis than OTL. There is no Vichy for instance to interpose; all of France is a direct Reich-occupation zone.
Aside from the starker fate of these hostages to fortune, the Allies are indeed considerably better off at this point.
So--whether it is possible or not, depends on whether Germany could have been squeezed harder to produce the necessary forces in time. Given that the timeline can go forward!