We are sincerely hopeful that this will not simply boil down to just a platform at Prince Charles's new housing estate at SW Nansledon.
A few other thoughts....
1. the line, and indeed a proposed Metro for the mid Cornwall area could be a good fit for a fleet 230's especially battery versions, given an under-capacity depot at BZ.
2. St Dennis junction to parkandillack trackbed is in situ and IIRC there is currently no clay running on what is left of the line.
3. Newquay platforms could be reinstated, although the former bay would need de-gardening and the other would only be good for short trains, as the foundations for the original 13+ coach platfrom are unstable, hence it being closed off c.1983. (Cannot recall which is plat 1 / 3 sorry!)
4. There is room for a small charging depot on the site of the former (later) sidings site at Newquay, for said 230's.
5. Passing places are possible on the St Dennis line, although they would probably have to be at Parkandillack/Treviscoe. Ideally the timings from St Dennis junction to loop would ned to be similar to that from St Dennis to Goonbarrow, unless a loop is/loops are provided at Goss Moor (St Dennis Junc.)
Making the South end of this line could be problematic, with several ungated crossings for some minor roads that, although narrow, are essential for a significant number of rural residents/businesses. It may be possible to re-align this section to avoid them and provide a triangle to the West of burngullow, and the western-most bridge. One is talking big big bucks though for that, (probably 15 million + alone)
6. If the St Dennis line was brought into use, both lines up to St Dennis Junction from the GW Main could be retained, with reasonable operating flexibility (one line facilitating a train Down to newquay whilst the other is used for an up train, then they swap over). However, a passing place would need to be placed somewhere between Newquay and St Dennis junction (this is the curve under the A30 at the Western ennd of Goss Moor for those that do not know). Probably St Columb Road Might be a good candidate, as a long loop, over an over-bridge, existed there until c.1965.
7. I like the idea of stations along the main line Metro-style - Charlestown, Carlyon Bay, Trewoon, Foxhole, St Dennis, Nansledon, Grampound Road, all spring to mind as possibilities, as well as several caravan sites situated along the line. With fast-accelerating Roling Stock with a corresponding gearing for c.70mph its all possible (like an adapted set of 230's). Park-and ride facilaities could be installed at St Columb, Roche and possibly Bugle, with advance booking and SPace-Reserving via Apps etc.
8. A line through Par docks area to 'cut out' Par for trains off the Goonbarrow/Bugle route is possible, the junction adjacent to BZ signal box would need to be upgraded for passenger use, and Par harbour crossing would need upgrading. The docks line could be used, and with the sparse remaining infrastructure in the docks area nowadays, a junction with the main line at Spit (like it was beofre 1968) is possible. Re-instating BZ as a Metro station is possible too.
Pint of Doom Bar, anyone??