If you really wanted to then you could go and stay at the Shatin Courtyard, it will only cost you HKD5-600/night if you did a long term rate and would be the cheapest way to maintain your status.

However, it's not worth it for another six years.... wait till your travel pattern returns. Based on what you did before I would presume that eventually your travel may return (over a 20+ year career) and you can start to click towards lifetime status. Even if you dropped down to gold, or silver, you could resume your normal patterns, or just ensure that your family holidays for the next 20 years include 2 weeks in a Marriott and eventually hit lifetime..... (20x20 = 400 nights :P)

As a Lifetime Titanium who has stayed in Marriott hotels in HK plenty over the last year (30 nights of staycations?) I would observe:
1. Upgrades for status are becoming less and less frequent as the hotels get busier. Sure I get plenty of nice welcomes, but it won't make a significant difference to be worth another 50 fake nights unless you do want a staycation every weekend.
2. The staycation hotel deals will normally replicate status benefits anyway
3. Your current status is, by HK standards, not that exceptional anyway, so whether Platinum or Gold I doubt it makes much difference (my view is that HK will have people like me with thousands of nights as a core loyal bunch, then the vast majority of people staying have zero Marriott status and are coming due to a staycation deal. Once normal travel returns (if ever) then HK will once again be full of road warriors that will also have platinum/titanium/ambassador status, but you won't be staying here then!