For sure, time is running out for a roller coaster in 2020. The only indication something could be happening is the apparent removal of Sticky Sisters and Burger King from the Old Town area, plus IMAScore tweeting about that area a few months back.
In terms of alternatives to a roller coaster, well we can be fairly sure it won't be a dark ride. Ghost Train has probably destroyed that idea across the parks for a little while. This would leave the installation of new flats, which wouldn't be a bad thing, but again not a particularly strong investment given the time since a fully new attraction. A hotel should be coming, but I suspect this would be budgeted from the Merlin hotel fund and be independent of other investment. Opening a new hotel without adding a new attraction for a good few years, well that's certainly Merlin management logic, but hopefully not what will happen.
Separately, Merlin and Thorpe are currently challenging a residential planning request that would be near the Thorpe Farm side of the park. Beyond regular noise concerns, they make specific mention of the last mid-term development plan and the principle of a 50m high roller coaster going on the site behind The Swarm. Whilst the reference is most-likely being made to assert potential developments the council is already aware of, it does show that Merlin considers this site and the mid-term plan as still being valid, despite being fairly out-of-date now compared to their original intention.
In addition, they make no reference to development permitted at Thorpe Park but not yet built, including the latest MTDP. This is a material consideration, most importantly because it established the principle of a 50m high rollercoaster on Area A, an island of land in closer proximity to the Cemex House site than the rest of the developed area. On the basis track noise including rollercoaster cars are currently audible on site, with significant noise levels recorded, a new rollercoaster in closer proximity will clearly effect the noise environment in this location. To restrict Thorpe Park’s capacity to invest in the park’s development would jeopardise its future. The Council will be well aware that the Park relies on the introduction of new rides and attractions to maintain its position as a leading regional theme park.