Hi there,
Congrats on your admission offer!

Your concern is valid. However, several Indian students attend top US B-schools without any financial aid (myself included). In fact, most of the top schools tend not to offer scholarships to students from India because of the competitiveness of the candidates.
The risk of not having visa sponsorship will always be there, but one way you can reduce your risk is to be proactive and get multiple job offers during recruiting. Then have all the companies file for your H1B and see which one gets approved! Yes, you can have multiple/ concurrent visa applications, so that increases your chances of a lottery. Also, if you will be attending a Top university, your visa is more likely to get approved.
Just in case, your visa gets denied/ rejected, having a US MBA degree with you can get you good offers back in India as well. At times some companies (like J&J) recruit in the US B-schools for international offices (incl. India) and would be open to giving you signing bonus that you can use to pay off your student loans.
On the other hand, it is also not uncommon to see bright students get good jobs/ visas only to be laid off because of restructuring/ company reasons. The point I'm making is that you can't really be entirely certain before you make either choice. You will have to take a leap of faith at some point.
Good luck with your decision!