Whilst we cannot really analyse the running cost figures for Valhalla, the evidence is there to suggest it took its toll on the park.
Pleasure Beach in the 90s was thriving, busy and appeared to be making money. Whilst Valhalla was a hugely popular and world-renowned ride when it opened, it also marked the start of the park's decline.
Valhalla opened in 2000, in 2001 three rides went SBNO. The high running cost and poor reliability of Valhalla took its toll and combined with the introduction of wristbands it's plausible to believe that the park could have gone from profitable to losing money rapidly.
You only have to look at how many rides have gone from Pleasure Beach since 2000 with no replacement to see that the park has not been in a healthy state for a long time. Whilst this can't all be attibuted to Valhalla, it was definitely after it opened that things took a turn for the worst.
Also consider, between 1994 and 2000 PB invested in The Big One, Ice Blast and Valhalla. Before PMBO they were also investing pretty well.
After Valhalla, it took 18 years before a new investment on the same scale was made. And the opening of this saw another coaster removed and overall park standards continue to drop. Says it all really.
Original Valhalla had a constantly cold room with ice and real snow being sprayed from the ceiling, much more fire than nowadays and a multitude of other effects (tesla coil, a better steam effect to the one used now) and with it originally running more boats and therefore triggering each effect more often, it's easy to see why the running costs were high. The ride system itself is also flawed, maintenance heavy and I can imagine uses an awful lot of power. The boats smash against the concrete/metal sides of the trough all the time which can't be good for maintenance. It's also had a number of quite concerning issues, particuarly in the last few years.
It's difficult (for me anyway) to watch that documentary and not be a bit sad at how bad PB let the ride get. It isn't even always the expensive things, little details like the style of lighting used or much more foilage in the ice room which has since been torn out and replaced with artificial Christmas trees. The ride has been treated so carelessly as a themed experience and it's such a shame because I genuinely believe it'd still be up there as one of the world's best dark rides if it had been looked after properly.
As for whether it will ever reopen, I really don't know. Let's not forget that Pleasure Beach told us the Wild Mouse was closed for "maintenance" before tearing it down in the closed season.
If Valhalla does reopen, I think it's likely to be a very cut back version compared with how it was even in 2019 (which was terrible!). Expect to see the fire replaced with timed lighting/smoke, no steam or ice, etc. Lots more dark sections.
Personally I'd rather see the ride replaced than reopened in a much less impressive state. If it opens after a year's closure with the majority of effects removed, that won't go down well at all. That said, the park have promised that it will reopen in 2021 so they'd have a backlash if it didn't anyway.