I really hope not, adding a permanent flat next year with high capacity and one with perhaps lower capacity should be fine for a bit and then they could replace blade an enterprise. I see no reason why they couldn't add a few cheap flats which will look better than these rides that are meant to be temporary and should be gone next year.
I just think that keeping the retro-squad demises the quality of the park overall but it also gives the park less flexibility. These rides cannot be treated the same as permanent ones, they are not maintained by Alton Towers staff and they cannot reach the capacity of a major flat if it's permanent and being ran by ATR staff.
X-sector clearly needs the added flat so something like a permanent themed version of mixtape with a higher capacity would be perfect but whatever they add it wouldn't be massively expensive and would look impressive enough for marketing material. In my mind this is the most important one to replace as it seems to have been a popular spot last year and that area of the park gets a lot of visitors with nothing to do for the families, or slightly younger thrill seekers who aren't quite tall enough for the smiler of oblivion.
Forbidden valley perhaps needs something however if they open something in the sub-terra building that would really help and that could potential wait a few more years. However they may well be able to get a bulk deal when they buy something for x-sector.
As for Dark forest it eventually needs something but I think they could get away with it for quite a while. Although I do think the area's theme would suite some form of tree monster, perhaps a magic carpet or something pretty standard but with tree trunks as supports would be cool and not ridiculously expensive.
Enterprise could be replaced relatively easy as there are plenty of second hand, but newer enterprises, although this might be less marketable so they may well want to go with something different.
Blade is a tricky one, ever year we think it's dead and then it comes back, its the oldest ride in the park and clearly needs a lot of maintanance. The area obviously fits a pirate ship quite well but adding another one wouldn't be very marketable, it will probably have to be replaced by something else eventually. I get the impression it will last longer than enterprise so perhaps replace that first and then think about something for blades spots.
I think the park have the chance to get somewhat of a bulk deal with at least a few of these rides and add them in different years. Making it cheaper but they've got something new for quite a few years. Clearly at least a few of these rides are needed at some point. I would like and almost expect at least one permanent flat next year, I didn't really expect any last year as I didn't think they've have time to asset how well the retro-squad did and then order a ride and get it installed on time.
I also have a feeling that the Retro Squad are going to be around for a while…
Also a list of what we could expect if they are to come back next year;
I am hoping this was just to keep there options open, I doubt when they planned these they had particular rides in mind they just used the names for whatever ride they could get there hands on.
Realistically, having the retro-squad long time would cost them far more than the cost of a few permanent flats surely?