Washington had the notion that these tribes would in time become fully equal to the white population, and the members of these tribes would become regular citizens of the USA. Jefferson later continued that policy to a considerable extent. The Federalist period in between didn't encourage these efforts, however. And after Jefferson, white settlers were already pushing into the region. This meant that "it's their land and they'll join us in time" became increasingly unpopular, supplanted by "it's our land, and we'll just kick them off it".
Mississippi attained statehood in 1817. Alabama two years later. That pretty much put the nail in the coffin for statehood for the tribes living within the confines of these new states. You need a scenario wherein the "civilising"/assimilation policy is pushed consistently, so that when the time comes to start dividing the areas in question (for the bulk, that means the 1810s), the general consensus is that the Civilised Tribes are ready for US statehood. This is not impossible, but you sort of need to destroy the Federalists to do it. Or put a Federalist in charge who wants to do it.
Supposing that this goes through, we'll see adjoining territories being fused together, no doubt. It won't be five extra states. More probably three. A Chickasaw/Choctow one and a Cherokee/Creek one in the 1810s, and a Seminole one in the 1820s. State borders are definitely going to be different in the surrounding region, all the more so because tribal statehood will be anticipated. Going off the tribal areas, one might see:
-- a *Louisiana that includes the coastal part of OTL's Mississippi but lacks its own OTL Northern regions;
-- an inland *Mississippi that lacks its own North as well as sea access, but includes OTL Louisiana's North, and thus straddles both sides of the river;
-- an *Alabama that loses good chunks of its OTL North, but includes OTL Florida's Westernmost regions, and;
-- A smaller *Florida Territory, soon divided into three parts (a Northern segment, a Seminole segment in the middle, and a Southern segment), all three of which remain territories for longer than united Florida did in OTL.
In addition, Tennessee would probably gain a modest bit of OTL Alabama (North of the Tennessee River) and Georgia would lose its North-Western corner. The overall result is two additional slave states, at least until the "Floridian question" omes into play. No doubt, the South will want to admit Florida as three separate slave states. This may cause major political clashes with Northerners.
(Of course, one possible outcome is that there is simply a wider acceptance of smaller states, leading the North to carve out a bunch of smaller, low-population free states to keep parity with the greater number of smaller slave states.)
