Solution:

To find the thousands place in the sum of the greatest 8-digit number and the predecessor of the smallest 5-digit number, we need to perform the following steps:

Step 1: Identify the greatest 8-digit number
The greatest 8-digit number is 99,99,999. It is obtained by taking the highest digit 9 in each place value from ten lakh place to units place.

Step 2: Identify the smallest 5-digit number
The smallest 5-digit number is 10,000. It is obtained by taking the lowest non-zero digit 1 in the ten thousand place and the lowest digit 0 in the remaining place values.

Step 3: Find the predecessor of the smallest 5-digit number
The predecessor of a number is the number that comes before it. Therefore, the predecessor of 10,000 is 9,999.

Step 4: Find the sum of the greatest 8-digit number and the predecessor of the smallest 5-digit number
99,99,999 + 9,999 = 1,00,09,998

Step 5: Identify the thousands place in the sum
In the number 1,00,09,998, the thousands place is the place value occupied by the digit 9. Therefore, the thousands place in the sum is 9.

Conclusion:
The thousands place in the sum of the greatest 8-digit number and the predecessor of the smallest 5-digit number is 9.