I'm happy your a re negotiating exit strategies already but may I ask - do you have a working business model (not a working business, a working business model)? If not, I would start with that...
As tou your question - exit strategies are fluid. You need to have one but why commit on one now? As long as there are options on the table for the investors to see their money back - if it's an IPO, M&A or distributing dividends the investor should be happy.
You may also change you mind about an IPO once you have the business up and running, so "never say never".
BTW- Uber is a service company ... if you have a good idea that can scale and you will be able to show the investors how fast they will see their money back - you will find investors.
If you wish, you can call to discuss negotiations and pitch strategies.