I personally think a swift change PoS rate from 70-100% to 2-5% is not a good idea, it's a very big change for a coin and its specification. I very much prefer a more slow gradual decrease on shorter intervals (e.g. instead of jumping from 100% in year 1 to 2% in year 2, we can do a slow decrease every 1-2 months until we get to 2% within 2-3 years).
I don't think the original developer thought about the long-term PoS issues of the coin, this is evident from the code he wrote but this is something that we need to decide.
Base on your idea, I make an example here:
171,000,000.00000000
Y1M1 199,500,000.00000000 100% //first 2 month, 100% best to attract people to invest and hold and stabilize the price after patch.
Y1M2 226,100,000.00000000 80% //another 2 month
Y1M3 248,710,000.00000000 60% //another 2 month, till here are the first half year, and have relative better interest than next half year.
Y1M4 265,290,666.66666700 40% //another 2 month
Y1M5 278,555,200.00000000 30% //another 2 month
Y1M6 287,840,373.33333300 20% //another 2 month, end of the first year.
Y2M1 295,036,382.66666700 15% //another 2 month
Y2M2 299,953,655.71111100 10% //another 2 month
Y2M3 303,953,037.78725900 8% //another 2 month
Y2M4 306,992,568.16513200 6% //another 2 month
Y2M5 309,039,185.28623300 4% //another 2 month
Y2M6 310,584,381.21266400 3% //another 2 month
Y3 316,796,068.83691700 2% //third year starts, 2%
Y4 323,131,990.21365600 2%
Y5 329,594,630.01792900 2%
Y6 336,186,522.61828700 2%
Y7 342,910,253.07065300 2%
Y8 349,768,458.13206600 2%
Y9 356,763,827.29470700 2%
Y10 363,899,103.84060200 2%