When we talk about “statehood” for any territory it always includes the possibility of incorporation into an existing state. That is why we speak about the “statehood model” that puts all states on an equal footing with uniform taxation and equal protection of law as the path to successful union.
Under its constitution and laws each state defines the territory over which it claims sovereignty, and Congress either ratifies the state boundaries or requires conformity with federal law defining state boundaries at the time of admission. The Constitution requires approval of the state legislature to form a new state from within an existing state, or to add a new state that changes the boundaries of an existing state.
Adding new territory to an existing state is in effect creation of a new state, and changing the borders of the existing state. Either way it requires consent of the state legislature. So incorporation of a territory into an existing state introduces the politics of the existing state directly into the federal admissions process.
At the federal level admission of a territory as a new state may or may not change the balance of power for the party in control of the U.S. Senate and/or House of Representatives. The political party in majority control of the new state may or may not change the balance of power in the Electoral College. Admission of a new state also may or may not impact the economies of other states, contiguous or non-contiguous. New states contribute to the national economy and security, but also add to the costs and burdens of federal government.
Similarly, incorporation of a territory into an existing state may or may not change the political balance of power in the state government or impact the economy of the existing state. Nevertheless, the existing state would have the power to approve or deny admission of the new state. Most territories seek admission as a defined body politic and all must have a constitution to be admitted. Thus, the territory to be incorporated must adopt the constitution of the existing state, and the existing state must change its constitution and/or laws as applicable in the new state.
In 1978 the Congress passed and the President signed a law enabling Guam and CNMI to form one territory. That has never happened because the powerful and wealthy elites in each territory do not want to give up or share control of their political and economic interests. The people who want to be Governor or in the legislature or a judge in each territory do not want to have to win election on two islands instead of one. In addition, the island with the most people would control the other.
All that is, of course, very short sighted. If the CNMI and Guam merged it would only take a few election cycles for the inter-island business and commerce that already exists to expand and for popular inter-island political leadership to emerge. As a united territory the two islands could try to leverage strategic location into a statehood bid, but it would be a hard sell. The other option would be to petition for incorporation as a county of Hawaii.
The same is true of American Samoa, which is Polynesian and incorporation as a county might appeal to Hawaii. But American Samoa is fiercely protective of its autonomy and customary way of life, and incorporation probably would not appeal to Samoans.
The Virgin Islands could become a county of Florida, or a county of Puerto Rico if it became a state. But as with Guam, CNMI and American Samoa, the local interests in the status quo would resist losing power and control.
As for Puerto Rico, it is too big to be incubated into an existing state. If incubated into Florida it would change Florida’s political and economic reality so radically the existing state would lose its identity. Puerto Rico could probably control the rest of the state because it would be the most concentrated voting bloc, and there are a million Puerto Ricans in other parts of the state.
The solution can not be imposed. No one solution works for all territories. Even a constitutional amendment is unlikely to resolve territorial status dilemma. Giving a territory representation in the Electoral College like Washington D.C. but not Congress is based on the same logic as the 3/5ths clause in the original constitution treating slaves as 3/5ths of a person for purposes of representation in Congress.
Either citizens in the territories have rights equal to citizens in the states or inequality persists. If territories can have equal rights without the burdens of statehood then states will want to be territories instead of vice versa.
Arguably, when the status of the last large and populous territory is resolved will it be possible to address the status of the small territories. Each has a right to separate self determination. The U.S. has that right as well in its relationship to each territory.
The idea of a pan-territorial solution is not thinking outside the box, it is the same old approach that produced the imperialist unincorporated territory status doctrine that applies to all the territories. That is another name for colonialism and only Puerto Rico has the political critical mass to be the first territory to break out and begin dismantling the unincorporated territory empire. That is thinking outside the box.