The way I thought it would go would be:
Then first bet is 2, so just using a long series of losses, the next bet would be 3 as in 2,2,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1, the next bet is 3 and as it lost the sequence would be 2,2,2,2,2,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1, - this then carries on until the sequence is all 2s. At this time the bet becomes 4 units, if this loses we have 3,3,3,3,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2. The next bet is 5 units and after the loss we have a sequence of 3,3,3,3,3,3,3,3,3,2,2,2,2,2,2,2,2,2,2,2. This continues until the sequence is all 3s then the next bet is 6 units for one bet then 7 units until the sequence is filled and so on until whenever ......
I havent worked out how deep this progression can go but I guess at some stage you will win 10 bets and the sequence will be completed. The difficulty as with all cancellation methods would be when the numbers in the sequence have been reduced from 20 to say 5 and then the bad losing run happens. At that point I suppose the string could be somehow expanded again.