Crossbuy can obviously be done only on a limited scale by 3rd parties. A more viable option could be achieving crossplay without additional costs if Sony released dev tools able to generate PS3 and PSV executables of the same game and sets of scaled down data for the PSV version (this could work nicely for devs not planning a PSV version otherwise, as it would give them the option to widen the market for the PS3 version), but 3rd parties won't do crossbuy easily unless Sony give them some incentives.
Everything helps, anyway, even if just a little, and another little but significant help could be a PS3+PSV+memory stick+game bundle within $400 (feasible just as time limited offer now, it will be also as regular list price after PSV will get a price cut), although, rather than a huge sales boost generator, it would be more a marketing operation aimed at avoing Wii U make current gen appear outdated.







