Hi I found your post to interesting and seems i have a narrow knowledge about Blockchain. i will contribute by answering your question.

Explain what you think message applications can do to improve reach to a wider audience?
I have used some of the blockchain message application.. and one of the ways they do to wider their audience is to the Used of sms in exchange of token that can be exchange for ethereum that. SMS that had not been used because people are communicating more on social networking app.

Eso may have a wider adoption in businesses but it can provide a good value to consumers too. What do you think would be a good way to market to consumers?
As of now many crypto Company are starting to used crypto as payments in major markets. but due to some country that do not support crypto had been the reason to limit the network of MArketing in using Crypto. They are already some good thing happen in markets to consumer.. and that is Trust,affordale,low-fees. Trust due to some Wallet reserve to refunds report products.Affordable due to discounts and tokens earn by the consumer in every transaction. Low-fees because most transaction fess are only around 1%-5%.

What can dApps, in general, do to on-board more everyday people?
Dapps Generally on-board more people everyday by providing security in info and date,prevent others people to access, entertainment where people can also earn like crypto kitties. Dapps provide wallet securtiy, good social network with security like peepeth, good crypto income and cash back through tokens like Bancor and many more.