There is no fuckup. SL will bent to the side having more economic heft and will play a China-India dance. Same like India is doing a US-Russia dance. Universal Truth
You are comparing apple to oranges here.
Do you see Mexico or Canada play US vs china? Do you see Laos Cambodia play US vs china?
What India does is very different because we are a power in our own right and are far away from both countries.
Your comparison makes zero sense because
1) Sri Lanka is at our border
2) Sri Lanka is no large country with resources of its own
3) they are a bankrupt nation living on our doles.
As i pointed out before no matter how great your economic or military influence it is very difficult for you to establish a foothold in a irrelevant country until and unless the nearby power in the region has managed to do a colossal fuck up.