I'm actually working on a timeline for such an eventuality, but I have yet to get very far (mainly because i'm doing it in the from of a series of book excerpts and quotations.)
In reality, I agree that such a proposition is pretty unlikely, but here's a very rough timeline, mainly discussing colonial expansion, not other stuff.
The Empire of the Kingdom of the United Netherlands c. 1924
POD: In 1813, the Duchy of Luxembourg never becomes part of the German Confederation. Consequentially, it is granted to William of Orange as an integral part of his united Kingdom of the Netherlands which is formed in 1815 (in OTL it remained in Personal Union.) With the extra Catholic and francophone influence of Luxembourg, the Dutch's attempt to assert protestant and Flemish superiority are moderated, and it is decided to have proportional representation, rather than the system installed in OTL (Dutch and Belgians got equal number of reps, despite larger belgian popualtion) In turn, less tension develops inside the Kingdom, thereby avoiding the dissolution of the Kingdom as per OTL. The stronger United Netherlands in able to demand that the British Return Cape Colony and the potion of Guyana that the British took control of during the Napoleonic Wars. In the Anglo-Dutch pact of 1822, the Dutch recognized British claims to the Indian mainland, Mallaca, and the remainder of the Malay Peninsula, it manages to regain Ceylon, which then becomes a Colonial territory.
The dutch then proceed to reassert their claims to the East indies, and with Batavia (Jakarta) as their center of colonial administration begin to conquer the sultanates of the region, where they had previously used indirect rule. All of Indonesia fall under direct Dutch Colonial Administration, with the notable exception of Sumatra, which is ruled by the so called "Sultanate of Sumatra." This Sultanate is an entirely Dutch Construct, designed solely to appease the islands indigenous populations which had provided fierce resistance. The First Sultan of Sumatra was installed into power by the Dutch, and was little more than a figurehead, with Dutch advisers responsible for the true management of the Kingdom. The successive sultans of Sumatra have all been dutch educated, and any notion of Sumatra Autonomy is illusionary. Indonesia has seen an influx of dutch immigrants, but not nearly as many as Dutch South Africa.
Dutch South Africa remains an interesting region. While the Original lands of Cape Colony were made an integral part of the United Kingdom (as apposed to a colonial administration) in 1875, and now votes in dutch parliamentary elections, the northern region remains a Colonial territory administered by a Dutch Governor. Despite attempts by Boer settlers to move into Lethoso, that Kingdom remains an independent entity, and the Dutch Governor has agreed to guarantee its sovereignty.
The Lisbon Conference of 1889 carved Africa up into several spheres of influence. As one of the three major colonial powers (the others being England and France) the Dutch were able to assert claims over the central African region of the Congo, and Ghana and Togo. Despite thier shared border, the intricacies of Dutch Colonial administration have seen Ghana and Togo remain under separate Colonial Authorities.
The Antartic expedition of Jan Verdonk (1900-1902) launched from Cape Colony saw the carving out of King's William Land as a Dutch territory of the Antarctic. In another expedition 1910, Verdonk and his party became the first to reach the south pole.
The Flag of the United Kingdom of the Netherlands, and the Dutch Empire
The current flag (as of 1924) of the Netherlands was implemented in 1815, on the centennial of the United Kingdoms foundation. The Flags Orange field represents the Flemish protestants, and the house of orange, while the tricolor in the lower fly represents the nations maritime nature (blue), the unity of the Kingdom (white) and the Catholics in the South (reddish-orange)