It's a funny situation the ICC have got themselves into, in many ways. I remember when I first joined this forum and first started taking a heavy interest in international cricket, there was a lot of criticism of the ICC for carving out "false" internationals teams. Below the Test nations we had Kenya, and then we had a host of teams that were based primarily on heritage players, ex-pats and the sons of ex-pats. Richard was often one to accuse the ICC of promoting these sides to make the game look more popular across the world than it actually was, and it was a common view.
Whether that was entirely true or not at the time, what the ICC have done with these nations have been, to a very large degree, a success. They've poured a large amount of time, effort and money into developing cricket in countries like Ireland, Scotland, the UAE and the Netherlands and providing the necessary pathways for countries like Afghanistan and Nepal to advance and join them through (initially) very low level international cricket. As someone who has watched a lot of associate and affiliate cricket over the last few years, let me tell any of you who haven't that the standard has absolutely gone through the roof. Ireland and Afghanistan increasingly get mentioned on this forum but it's not just them; it's often said that the likes of Canada, Kenya, Namibia and even Scotland have "declined" and while it is true in some ways, it's been more about the other teams just improving past them. Realistically Scotland have a better side in terms of their skill base than they did five years ago; it's just no longer the gold standard of associate member cricket.
As they say though, be careful what you wish for. The ICC developed Ireland and Afghanistan to a point where with equal funding and exposure they could join Bangladesh and Zimbabwe very quickly; hell an argument could be made to suggest they've done so already and would likely pass them. But now that the ICC actually have more than eight to ten serious national cricket sides, they don't quite know what to do with them. The "pipe dream" was always to spread the game and create more Test sides, but fitting in twelve Test sides to an already busy international schedule is a massive challenge, particularly when the lower sides that already exist just aren't profitable for Test cricket in terms of gate receipts and TV rights deals (as an example, the money Zimbabwe get every time they play India has to last them until the next time they play India as literally all their other matches run at a loss).
Cricket, like a lot of other sports, works in four year cycles. An ODI World Cup every four years, a T20 World Cup every four years, a home Ashes every four years and an away Ashes every four years - all the big events roll around in that cycle (or are supposed to anyway..) so four years is looked upon almost as the length of an entire international cricket season. If each team played two home Test series and two away Test series every year then they'd play against eight other sides, home and away, in a four year period. Including themselves that's a pretty ideal sounding four year round robin for nine Test sides, and although the ICC have had some significant problems with the FTP, that's basically the structure they've looked towards. To expand Test cricket much beyond nine or ten you'd have to extend the cycle to five or six years (which would be a big financial drain on cricket with less regular show piece events), create two tiers with promotion and relegation (what they've proposed, but would no doubt exasperate the financial inequity between the boards) or just scrap the FTP altogether, which would do nothing but create a less fair and equitable version of two official tiers, with the big countries only playing each other regardless of where they sat on the rankings and the lower teams not bothering running Test series at massive losses, particularly with the ICC grants having been cut to support the new teams.
One idea would be to recognise that while spreading the game across the world and providing tangible pathways for young cricketers in other countries is desirable, eight or nine just works best for the international schedule at the moment. We already have the England (& Wales) Cricket Board and the combined West Indies regional side, so it perhaps wouldn't be a stretch to convert some of the other boards in a similar way. Given the close political and geograpgical links, we could have the Board of Control for Cricket in India (& Nepal), with Nepal introduced as a Ranji state side; the ECB could become the European Cricket Board with the County Championship expanded to include Scotland, Ireland and Netherlands; Cricket South Africa could become Cricket South(ern) Africa - Namibia already field a team in South Africa's First Class system and Zimbabwe quite easily could too. The complex political situation may prevent the formation of the Pakistan (& Afghanistan) Cricket Board, and I bet the Quaid-e-Azam Trophy players wouldn't be too keen to travel over the Pakistan/Afghanistan border to play a game of domestic cricket, but it could be worked towards too. Given the reality of the situation in England with any European players of calibre highly likely to take up County deals and quality for England - as we've seen - and the likelihood of Ranji teams doing similar things with Nepalese players in the future should they continue to develop, this would merely provide pathways for these players, give them access to the high quality facilities, coaching and money available in the big countries and actually give them official representation at the highest level, much like Wales. Of course, given this is already the unofficial reality of the matter, the big countries have very little incentive to do such a thing. Instead they're having a whinge about having to play New Zealand twice every four years.