There’s actually not that much that can be done to protect against collapse during the transition period as the developed world already depends on 3 major things, none of which would have good workarounds during a transition:

• Electronic communications - necessary to make global shipping, banking and government systems function
• Global shipping - currently heavily subsidized by the US navy’s military presence, though other nations such as china are starting to invest further on theirs.
• Cheap energy - The Energy Trap explains the problem much better than i can, but basically energy needs increasingly more energy to obtain and societies haven’t done nearly enough preparation against this.

The only viable workaround for the first 2 is avoiding WW3. The third one could be worked around by using nuclear fission as a last-chance energy loan to finance a full-scale energy transition towards renewables(or praying for a hail-mary in experimental fiends such as hot fusion or lattice confinement fusion). The opportunity windows for all of these are quickly disappearing and may be nonexistent in some regions already.
There are other global-reliance systems which at least have some potential workarounds (such as the networks of debt), but overall they’re smaller concerns compared to these, at least in the immediate-to-medium term.

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The main other major concern i have in the non-global category is subversion of the government structure, which i tried to harden the government system against by avoiding the use of representative-based democracy and by requiring laws to affect everyone equally, as existing governments have demonstrated distributing power, even among a few thousands of people, still isn’t sufficient to prevent corruption.
The goal behind the waiting period before ending autocractic rule was having enough societal progress happen that enough people have enough of Maslow’s hiearchy covered to protect enough against this subversion happening on the millions-of-people scale. Without this progress in place, masses would likely vote themselves increasingly more leading to economic collapse.

I couldn’t find a way to get rid of the electronic communications demand. The implementation of the capital tax, UBI and direct democracy voting systems need too much data input/storage/output (roughly estimating within an order of a terabyte per year) to be feasible without that, even though the computing could be doable on government-operated computers (ranging from vacuum tubes to micromodules in the scale of integration / miniaturization - electromechanical and below is definitely out of the question).

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Despite the problem of reliance on the above, post-scarcity doesn’t actually need a global supply chain - having one just makes it a hell of a lot easier to achieve. Rather, post-scarcity only needs enough productivity to beat society demands on voluntary mass unemployment, and this has already happened on some areas such as agriculture through synthetic fertilizers (increasing production) and large-scale mechanization (decreasing labor requirements). This completed the last requirement in the biological step of Maslow’s hierarchy at the cost of limiting crop variety - most of the bulk production is now on corn, rice, wheat and potatoes, all of which are susceptible to climate-change-induced-collapse.

Besides increasing production and decreasing labor requirements, other means to achieve post-scarcity are decreasing society demands (which has historically been done through practices such as senicide and other targeted forms of social/ethnic cleansing, though i believe can be avoided at the current technology levels), and increasing voluntary employment. These last two methods were a significant part in the elaboration of the principles behind my top-level comment’s plans, as they’re the major parts capitalism has failed to focus on.